Any HVAC techs up in here? Need some advice please!
3First, it’s gonna be 108* here for most of the week, so I really need to get to the bottom of this…
I woke up early Sunday morning to an inop heat pump. Compressor was working, but blower motor was not. I fussed with it for a bit, checked the cap, eventually decided it was a relay not activating properly. So I bypassed the relay, and left the blower in “always on” mode. Ordered a new relay (it was delivered today).
That seemed to be a workable temporary solution. The blower spun up and everything was grand all day Sunday. Monday morning I woke up to 90* temp in the house. The blower motor locked up sometime during the night.
Motor spins freely by hand, without any electricity, but the moment the system kicks on and power is applied the motor is locked. Won’t spin by hand, gets hot, and buzzes.
Ok, so bad motor, right? Tonight I replaced the motor with a new one. All specs match the old motor (208-230v, 1075rpm, single phase, etc).
The new motor spins up just fine. Everything functions as expected… except the motor isn’t moving much air. Hardly enough airflow to feel it at the register.
It’s a 3 speed motor, so I double checked the schematic to make sure I didn’t accidentally connect the low speed lead… but it’s definitely connected correctly.
Obvs I can’t let it run like this. It’s likely to freeze the evaporator, but even if it doesn’t, it’s essentially useless. It won’t keep up with 108* outside temp when it’s barely trickling any air.
If you know anything about HVAC, I’m begging your advice! Please!
- 19 comments, 121 replies
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You’re sure it’s not the cap? Caps are usually the first thing to go and will keep your motor from spinning up.
I’ve never had the blower motor cap let go but have had three condenser fans at three different houses do it over the past several years and these are the exact symptoms, not spinning, buzzing and hot.
@djslack yah, would be worth simply swapping out the $30 capacitor to see.
@djslack I agree. The cap is more than likely the culprit here. I had a very similar issue a few years ago and after doing much of the same process, it was the cap.
@djslack I try to replace caps on most motors every 8-10 yrs. On my aging heat pump, I also added a hard-start kit (additional cap) to give it a good start. It’s so easy to just change them out & the motor will love it. Write the date on the cap so you know how old it is. I’m changing out caps on my well-pump today. found the old one leaking after just 9 yrs. It’s hard to find caps where I live, I had to order it from Amazon.
When operating, was the line good & cool? Have you cleaned off the coils inside & outside?
I’d (carefully) double check voltages & check amp draw for the motor when it’s running.
@daveinwarsh @djslack @capguncowboy Cap tested good with DMM. Also, the cap is newish. The exhaust fan cap failed in February, so I replaced all three caps since I had to crawl on the roof and open the system. Finally, I also swapped the blower motor cap and exhaust fan cap just to be sure. No success. That’s when I decided the motor was toast.
Usually with a failed cap you can still spin up the motor by hand and get it running. The old motor was totally seized when power was applied. I figured this was a shorted armature, etc?
@daveinwarsh, I have a start cap on the compressor and run caps on the exhaust and blower motors. I hadn’t thought about writing the date on the cap. Great idea. I’ll start doing that from now on!
@daveinwarsh, other than the blower motor, the rest of the system is working well. Because of the excessive heat, I had to come up with a solution or the dogs would drop dead inside the house while I’m at work all day. I rigged up a makeshift blower using a fan inside the house, forcing air from the filter return inside the house. With that fan blowing through the return, the system blows nice cool air.
My frankenblower. Taken from the floor, looking up at the ceiling. I removed the filter and mounted one of those air circulator fans to the ceiling, forcing air into the system. I used some Priority Mail boxes to create a shroud. This pic is taken from the floor, looking up at the ceiling in the hallway.
It appears you already know a hell of a lot about HVAC! Seems like the things I would have tried.
Have you checked all the wiring and the connectors? Couldn’t bad connections not allow enough current to flow, over heating the motor and slowing its performance? (I’m assuming it is direct drive so no belt!)
Otherwise, this might be the time to spend the $100 on a diagnostic service call by a trusted HVAC company.
One last thing that many years ago alerted me to the failure point of our central AC - that starting capacitor - cost $30 instead of $150… do you have an HVAC parts supplier warehouse/store nearby? Running thru the problem face to face with them might point to the problem.
(If you’re really lucky there will be several HVAC repair guys picking up parts and competing to solve your problem over coffee!)
@RedOak I stopped dealing with HVAC service companies.
Of the last 3 I had out here, all 3 told me the system was gasping it’s last breaths and was going to experience catastrophic failure any moment and I had to replace the system immediately.
The last service company told me the system was unrepairable and needed immediate replacement.
That was over 15 years ago. Apparently “on the edge of catastrophe” can last at least 15 years.
@RedOak @ruouttaurmind The companies around here won’t even want to consider my unit, which is original to the house. I won’t blame them, though – when I bought my house, the “last service” date was 1982.
@narfcake @RedOak @ruouttaurmind LOL… Our heat pump is from 1984. I’ve kept it going (knock on wood) for quite a while. I’ve only had to top off the r22 a couple times in 30+ yrs.
I really can’t say enough to people to just keep your damn coils clean. Run a quality inside filter, not those fiberglass crap things. Use filters rated merv 10 or higher.
A failing capacitor will cause a lot of stress on a motor. Just slap a new one in every 8-10 years, it’s so much easier than replacing motors. On aging compressors, consider a ‘hard start kit’.
@ruouttaurmind yep sounds familiar. Tough to find one that isn’t focused on a complete replacement.
We were taking care of a home in an estate and to keep the backbiters at bay simply used the same HVAC company the owners used to diagnose a furnace problem. It is one of the biggest, “most reputable” companies in the area.
They quoted $800 to replace the exhaust ventilation fan and said the (6 year old furnace) needed to be replaced.
I checked with a local parts supplier and the retail (not contractor) price for that fan was $175.
@RedOak
There was a hidden camera expose on one of the local TV stations. They had a tech check out the system in a house to make sure it was operating correctly. It was an older house, with an older system, but in perfect working order.
The tech then swapped in a known bad cap, and the reporter scheduled service visits with various “biggest, reputable” companies in town. Of the 6 service techs, three wanted to replace the system, one guy replaced the cap, but charged $300 (for a $10 cap!), one guy replaced the cap and charged about $100, and the last guy replaced the cap, charged $20 for the part and waived the service fee.
@ruouttaurmind
@RedOak My neighbor got a quote for “replace the whole unit”. Instead, $140 for a new motor/capacitor/mount and $50 for my labor, and it’s been fine for 4+ years already.
@narfcake @ruouttaurmind really makes me sad to think about all the folks who don’t have enough mechanical knowledge to sniff a scam. We have several older neighbors and I try to caution them about these abuses.
And sometimes it isn’t blatant dishonesty - it can be simple ineptitude.
When we bought our home many many years ago, I followed the home inspector around…
(you should not find the inspector via your realtor due to the potential conflict of interest… and even if you have no mechanical knowledge, you should personally witness the inspection. You can learn things that don’t end up in the report)
… when it came time for him to check the furnace and hot water heater for CO leaks, he found none. Out of curiosity, I asked him what would have happened on his instrument if he had found a leak - would it beep? I asked him to stick the probe in the (running) hot water heater flue. Silence. He turned three shades of red embarrassment and apologized he had not calibrated the instrument.
@RedOak What is a hot water heater? If the water is already hot, why do you need to heat it? Shouldn’t it be called a cold water heater because it heats cold water?
@ruouttaurmind Just out of curiosity – are the coils clean or are they restricting airflow? I only ask because they could restrict airflow. I know it’s a long shot, but I’ve seen it before.
@capguncowboy Clean enough as to not restrict airflow with one side of the air plenum removed for access to the blower assy. When the new motor runs it’s obviously slower/quieter/less powerful than the old motor was (when it worked).
@ruouttaurmind Was a run capacitor part of the new motor?
Since the old one spun but wouldn’t properly energize, I’m kind of leaning towards its run capacitor being the culprit (and not the motor itself).
@narfcake The old motor would spin by hand when the power was off. When power was applied, the old motor would seize up. Wouldn’t spin by hand, and would just buzz and get warm. This was with two different run caps. That’s when I decided the old motor was toast.
Also, after the first night, when I thought I had a bad relay, the old motor was running constantly for about 24 hours, then just… stopped and that’s when it started the symptoms which made me believe that old motor was failed.
@narfcake @ruouttaurmind I was following this conversation til I got to plenum … what the heck is an air plenum?? (FYI, dictionary was NOT helpful! 1. an assembly of all the members of a group or committee.
2. PHYSICS a space completely filled with matter, or the whole of space so regarded.)
P.S. sorry I have nothing to add but a question.
@mikibell * looked up “air plenum” https://en.wikipedia.org/wiki/Air-mixing_plenum
@ruouttaurmind Ah, so probably an internal short, then. Not common, but it happens.
@mikibell An air plenum is the main duct leading into or out of the unit.
@therealjrn wikipedia?? sigh… do I have to have the same conversation with you as I do with my children when the cite wikipedia??
@mikibell I’m sorry. Our family copy of the World Book (1966 edition) was donated to the restore when Mom passed away. If I had known I was going to need it today, we would have hung onto them.
@therealjrn That’s newer than the edition we have.
@therealjrn
(sorry about mom)
@narfcake thank you, Narfy!
@narfcake Does your edition cover the Air Plenum?
@narfcake
Yup, I’m thinking an armature short in the old motor, and possibly a bad new motor.
I ordered another new motor from a different source. It’s the same brand, model and specs as the original motor (which worked fine for two decades). It will be here tomorrow (Wednesday). I also ordered a pair of caps. Two different brands, just to be safe. They’re cheap as chips and it never hurts to have a spare on hand.
I only have to get through one more night of that infernal roaring frankenblower configuration. At least it’s comfortable in the house (all the noise not withstanding).
If the new, new motor doesn’t solve the problem, I will admit defeat and call a professional. After all, I haven’t heard the “you need a new system” sales pitch in years.
@mikibell Sounds like you’ve gotten to the bottom of the plenum mystery. Sometimes called an air handler, air exchanger, or “that big metal box with all the empty space inside”.
@mikibell @therealjrn
Except that wikipedia was correct, and better than whatever dictionary you used…
@mikibell @therealjrn
Why I tell all the college students I teach that everything you read on the internet is obviously true and so why on earth do we even need libraries these days. All your tuition dollars and tax dollars are just being wasted. Right?
Actually I read something or other several years ago that when someone did actual real research (did not read on the internet, rather peer reviewed journal online when looking to create a “why it will not be accepted to cite the internet unless you can also find the same article in a library database” document for same, said students) they found of the random sample of 300 or so wikipedia pages they fact checked, roughly 1/3 of them had wrong information on them and about 1/5 of them were pretty much far more or completely fiction rather than fact. (And no I don’t have the cite for you because it is buried somewhere in my files and on a blackboard account I can no longer access so you are just going to have to believe what you have read on the internet - by the way, rocks can fly. You heard it here first and this is the internet so it must be true
)
@Kidsandliz @mikibell You can not cite your work? Pity.
@mikibell @therealjrn Yeah can’t find the word doc - might have not made it over from work’s hard drive. If my wait in the doctor’s office is too long today and if they have internet I could try to find it again (it is 110 miles from here like everything else is, gotta leave in a half hour). Was rather interesting.
@Kidsandliz
/wootstalker https://shirt.woot.com/offers/the-internet-is-never-wrong
The Internet is Never Wrong!!!
Price: $19.00
Condition: Probably New
Not an expert, but I’d ohm-out the motor leads to make sure your schematic is correct. Or just try the other leads.
@walarney I tried each of the three speed leads, just to see if some knucklehead on the assy line was asleep at the switch when the leads were attached. Nope, all three leads provide about the same response. Motor spins up fine, but it’s like it’s running on low speed, no matter which of the three leads are attached.
@ruouttaurmind Could it be a bad motor?
@narfcake Ya, I mentioned this above. Could be a burned up original motor, followed by a bad replacement motor. Second new motor on the way. Will be here Wednesday.
Are you using a nest or similar “smart” thermostat? I had similar issues before I swapped it out for a non smart one because the nest was pulling too much power from the unit.
"It appears you already know a hell of a lot about HVAC! "
for the meh community
I saw this post 20 minutes after you put it in and thought “dang, now I need to add learning HVAC to my bucket list” - I already plan to take an automotive course “someday.”
I’m so glad others here have that knowledge and shared, hope something here helps!
Do learn it, it’s actually a blast! (sorry)
A slew of shady HVAC companies also led me to learn. I later wound up installing minisplits throughout my house, and for friends and family. My approach has been to put the money I’ve saved into tools and equipment. I now have nitrogen gear, recovery machine, micron meters, digital manifold gauges, and a bunch of the usual stuff. Minisplits slashed my electric bill from $400 to $130 in the worst of summer (Florida!). That’s with running a cooler temp than before, and house occupied about 23/7.
Anywho, one trick I’ve learned is to pseudo-rent a portable AC when the main is down. Buy a portable, ideally off of Craigslist or something, but a brand new one will also suffice. Use it till you calmly fix your main AC. Then, sell it back on Craigslist for what you paid for it. If you got a crazy good deal, you might even sell it for a bit more. If you bought new, keep the box and everything so you can sell it for a better price and only lose 30-50 bucks. Please, don’t just return it to the store, that’s sleazy, and just drives up prices for everyone else. This really takes the pressure off and protects you from hasty and/or costly decisions.
HTH!
@jester747 Ya, if I had known this was going to drag on for so long I definitely would have bought a portable unit. In fact, last night I was so desperate for sleep I checked my local Walmart for a cheap-o window unit. As fate would have it, my local store is remerchandising right now, so a very few fans and no A/C on display.
@jester747 @ruouttaurmind try home despot and lowes, and Ollies, and big lots.
Oh Amazon, how I hate thee? Let me count the ways…
Imma go with 111 ways. Once for each degree of temp outside right now, and Amazon failed to ship my replacement blower motor in a timely manner. Instead of being delivered today, it’s now been updated to Thursday. And it’s 111 degrees outside right now.
I swear, if I don’t get a decent night’s sleep soon I’m going to go on a rampage!
@ruouttaurmind buy an 8000btu haier and tape in a bedroom window at least you can get some sleep.
@cranky1950 I finally admitted defeat last night and ran to Target 5 minutes before they closed. I bought a 10K BTU Haier for way too much money. I was up until 1AM installing the “easy to install” window unit. LOL!
Today I’m going to hang my head in shame and call in a professional. I’m confident I can resolve this… if it was March or October. But not in June when temp is supposed to reach 113* today. I just can’t wait anymore. Hell, the cost of that window unit likely would have paid for the repair two days ago.
@cranky1950 @ruouttaurmind 113 degrees? Shit!
Yeah, there’s a time to call someone in for help. I’ve purchased bad motors before, I wonder if that’s it since you’ve checked everything else.
That window-shaker should help you to sleep until repairs are finished. I sure hope you can find a reputable person to check your system.
Be sure to let us know what the problem was.
One more thing I’ve used to find solutions to things everyone else gave up on: A non-contact thermometer.
Run the system for a while. Shut of all power. Search for breakers, wires, connectors, anything running hot when it shouldn’t.
@daveinwarsh Nothing is running particularly hot, but there is a relay that’s making quite a bit of noise. I’m hopeful it’s as simple as that. $55 service call, maybe $30 or $40 in parts, then finally a decent night’s sleep.
I’m already into this project for over $400 including the window A/C unit, new motor, caps, and a big fan. I have learned… next time something like this happens in the middle of the summer, just suck it up and call in the pros.
How long has it been since you cleaned the evaporator it get full of dust and mold eventually and causes the fan motor to overwork. shoot down with bleach and water let it stand a bit, then rinse with the garden hose. or use a pressure cleaner if you have one.
Check your mains and make sure both 110 legs are hot. Brown out time seriously messes with breaker contacts.
@cranky1950 Getting a solid 224VAC at the blower motor. But the motor is running like it’s only getting 110v.
Spin it by hand and see if the 2ndary windings kick in if so you got a bad starter or bearings. That 's how the condenser fan on mine acted when it was going bad, and I would spin it fast enough to kick in the high speed windings and it would run normal until the thermostat shut it down.* Careful of your fingers, don’t wear gloves.
Wait! Shhhhh… hear that? That’s the sound of cool, comfortable air whispering through my vents.
There was a cooked relay which was causing a ground fault in the blower supply. The tech speculates one of two possible causes:
or
The new motor was essentially using 120v of the 220v supplied to it, resulting in 1/4 speed and torque. Unfortunately it also cooked my wifi thermostat, causing the fan circuit to be in “always on” mode. Thank goodness I’m a self-proclaimed pack rat, and I saved the old manual ‘stat for just such an occasion.
I guess I don’t feel so bad about not resolving this on my own now. It took the tech nearly 3 hours to track down the final solution.
Damn this has been a very expensive week. $80 for fans, $120 for a motor, $300 for the window A/C unit I bought last night, and $190 for a tech. I really don’t want to tally all that up for fear it will harsh my buzz over finally having the A/C back in action.
Many thanks to all who pitched in with suggestions.
@ruouttaurmind
$690.
@ruouttaurmind
Oh, and don’t forget about anything which you had which could not withstand the heat.
And any suffering you dealt with, also counts.
@ruouttaurmind glad you’re cool again and you know what the problem was. Your thermostat failure made me think… I bought an ecobee3 really cheap at Lowe’s off a clearance table this past winter to install on my second unit (been rocking one on my main unit for a while now). When I finally got around to installing it, I noticed it had been opened (it was obvious inside the box, but the outside seemed untampered). It still had someone else’s account in it, and it caused the fan to run the whole time the unit was powered on. I wondered what kind of failure mode would cause that.
It was well past the timeframe to return it to Lowe’s so I decided to call Ecobee. Their support was super nice about it and sent me a new exchange unit (actually an upgrade to the 4) although it took about a week of back and forth with them, sending a few pics of wiring, and wiring it several different ways to confirm the fault. The rep did mention once that an internal fuse could blow causing the fan output to stay on.
I hate that someone was shady and burned up their thermostat then returned it to the store but I’m glad that ecobee stood behind their product. If yours is an ecobee maybe they can help you get it serviced for less than the cost of a new one - they may even be interested in finding out how a blower motor/relay failure can take out the internal fan relay.
@PlacidPenguin Thanks for that. Good to know I can count on you to bring it back down to earth.
@djslack It’s a Honeywell ‘stat. I plan on contacting them on Friday to see what my options are. On the plus side, most of the cost of the unit was paid for with a utility company rebate. So if worse comes to worse, I got use of it for nearly a year at practically no out of pocket. If I have to replace it I’m probably gonna shop out a Lyric. I’v been satisfied with the Honeywell app and cloud, and the Lyric has better IFTTT integration.
@ruouttaurmind
Sarcasm?
@PlacidPenguin More like self deprecation.
@ruouttaurmind
On the bright side, you have quite a bit of
freepeanut butter juice.@PlacidPenguin
@ruouttaurmind
How about making peanut butter ices (ice pops)?
@PlacidPenguin @ruouttaurmind The schadenfreude is strong in this one.
The topic that just won’t die…
Son of a biscuit.
So the A/C tech was here on Thursday afternoon. By the time he left, the system was blowing nice cool air at a reasonable volume. Sometime overnight while I was sleeping the “slow blower” problem returned. System activates as expected, but airflow is barely a trickle. Frack!
First thing this morning I called the company. They sent the same guy back “between 10AM and 3PM” (grrr! I shoulda been bumped to the top of the list…). I was hoping they would send someone different because a fresh set of eyes on the problem couldn’t hurt.
So the guy showed up at about 2:30. By 5:30 the system was back to functioning properly. Cool. So I run out to the office for a few hours, and when I came home… same fricken problem! Deja vu all over again!
It’s too late to call them tonight, but I’ll try first thing in the morning. I’m assuming this time of year they must work on Saturdays. But I’m definitely not looking forward to sitting around for another full day waiting, only to repeat the same crap. He didn’t charge for his service call today, so I guess as long as there continues to be no charge I’ll give him another shot. But at this point I kinda want my money back so I can try another company.
@ruouttaurmind Hmmm… I replied & it disappeared… TESTING…
@ruouttaurmind OK… Try again…
Wonder if the relay went out the second time or if it was something else.
I’d recheck 240v & 12v voltages at different spots on unit, check amp on motor & the whole unit again.
@ruouttaurmind I agree that a different tech may find a different issue. I’m glad you have that window shaker to keep you semi-cool.
@ruouttaurmind around here a bunch of HVAC companies are 24/7 in the summertime. I mean I bet you pay more to have them out at midnight but they are willing to do it.
Sounds like there may be a fault further up the line in the control board that’s taking out relays? Assuming the second relay also became bad… Have they changed the whole board yet? Also, have y’all cycled the the unit off and then back on when he gets it working? Wondering if it’s something that happens the first time it cuts off or even something going on when it’s in off mode that’s cooking the relay? Maybe even something that requires some time in off mode, like an actual cycle versus just turning it off and waiting five minutes to restart the compressor?
@ruouttaurmind
Since it seems that what’s happening is that it’s not always getting the full 220v/240v, and since the relay (contactor) has been replaced already, could it be the circuit breaker itself that has a weak contact and causing one of the legs to cut out?
@narfcake @ruouttaurmind A breaker will wear out if it trips a lot. Usually (not always) if a contact on a breaker starts to go, the breaker will be warm.
@narfcake I mentioned the breaker to the tech and he made a good point. The compressor also uses the same breaker, so he would expect to see problems there as well. Makes sense I guess. The compressor draws quite a bit more current to start and run than a simple blower motor.
I had another thought tonight. Based on the symptom (slow blower, no torque) it almost seems like it’s running on 120v instead of the 240v it needs.
Anyone who’s familiar with 240v help me think through this please…
So 240VAC is basically two 120VAC potential leads and one neutral (or earth/ground). If there’s an open neutral connection… you still have 240v measured between the two potentials, yes? So what happens to a motor if it’s seeing both potential supplies, but no neutral? Does it run?
OTOH, if the motor has a solid connection to neutral, but one potential is open, it’s only seeing 120v, yes? Will it still run, but at degraded performance? I know if I connected a 240v motor… the two incoming potential leads… if I connected those two leads to a 120v outlet, the motor will run, but at about 25% of it’s rated RPM and torque.
So in the case of my 240v blower motor, if only one incoming lead was connected to one leg of the 240v potential wires, and also the motor was grounded… will it run, but at 25% performance? That’s the symptom I’m seeing here… the blower is running, but only at a fraction of it’s normal operating speed. To complicate troubleshooting, the problem is intermittent. When the tech messes with the system it starts working again. After a bit it reverts to slow performance. If I wait long enough… it starts working again.
I’m just trying to wrap my head around what can possibly cause the motor to run like it’s getting 120v, but 240VAC motors are a step above my paygrade. I know very little about 240VAC in general, and less about 240VAC motors.
@ruouttaurmind Internally broken wire, perhaps? Jiggling made it work & not work.
@daveinwarsh
When he came back today he didn’t replace anything. He opened the system, fished around a bit, measured various voltages and resistances, double checked his connections and the run cap, scratched his head and turned the system on. It just worked.
Same thing tonight. When I got home from the office, it was malfunctioning again. I turned everything off, waited a couple hours… now it’s working again.
This time I turned the ‘stat fan setting to “on” to keep the blower running. I’m curious to see if the problem returns if the motor never turns off.
@ruouttaurmind I’m stepping a bit outside my area of expertise in 240v as well, but doesn’t the motor just connect to the two hot legs to get 240v? The neutral is only there to provide a 120v circuit as I understand it, one for each leg of the 240v circuit.
There could maybe be something funky (akin to a floating ground in DC parlance) where one hot leg functions as a neutral and you get 120v, but how would this happen only sometimes? And how would you still measure 240v when it’s going on?
@narfcake
This is my thought process for trying to learn what happens when only two of the 3 240VAC leads are connected. One of the 240VAC potential motor wires terminates to a power buss. I’m wondering if perhaps there’s a hairline crack in the buss contact or rail. Or perhaps, since the blower gets it’s neutral/ground from the chassis by way of the blower housing subassembly… perhaps the housing isn’t making good contact with the chassis.
Sliding out the blower housing, then back in could resolve the ground problem temporarily, but after the blower rattles a few times from starting running and stopping, maybe the bad ground reappears. Or, as the A/C runs, the housing gets cold and contracts, causing the grounding problem to reappear?
@djslack
I suggest a couple of possibilities in the post above.
As far as neutral being unnecessary for 240VAC, my clothes dryer doesn’t agree. When the plug wire frayed and neutral broke a few years ago, the dryer was inoperative until I repaired it. BUT… I know next to nothing about 240VAC, so I’ve asked you all to help me think it through.
@djslack
This system is pushing 40 years old. It has no control board. The relays are powered by a 24 volt transformer. The thermostat is connected to the relay. When the ‘stat kicks on, it triggers the relay, which closes one leg of the 240VAC supply to the motor. That’s the entire blower circuit from soup to nuts.
But you bring up a fair point… now I’m wondering if the 24v transformer may be getting weak and not fully closing the relay contact? A very poor connection would still provide current, but at reduced levels, yes? Once the system is turned off and the tired transformer has a chance to rest and cool off… everything works again for a bit.
Last night when I got home from the office, without knowing exactly how or what I did that worked, I managed to coax the blower motor to run at full speed. Then I set the thermostat to run the blower constantly, and selected a comfortable temperature setting.
This morning the blower is still running correctly at full speed. Throughout the night I could hear the compressor kicking on and off as expected, and the blower running non-stop. The temperature inside the house is a brisk 83*, right where I set the ‘stat.
So as long as the motor never turns off, I guess the system is functional. At least I’ll make it through the weekend and might actually catch up on my sleep!
As far as the underlying cause of the motor intermittently running slow… dunno. The tech immediately blamed the new motor as defective. But this is the second replacement motor exhibiting this same behavior, so that’s highly unlikely. (The first replacement motor was a used motor from Craigslist, the second a brand new motor from Amz).
I still need to solve this challenge, but least I’m nice and comfy for now!
Blower has been running nonstop at full speed for around 32 hours. I’m tempted to switch to “automatic” mode to see what happens. My bet? The first time the thermostat cycles, the blower motor will run at reduced speed again.
@ruouttaurmind I’ve been following this thread from the beginning, and I’m eager to see if you ever discover the culprit! Glad to hear that for now at least, you’re cool.
@PooltoyWolf I appreciate that! Thanks.
The service company’s “old timer” is supposed to meet the original tech out here this week. I’m hoping the seasoned veteran tech will have one look, smirk a bit and say something like “well there’s yer problem right there… on these old electromechanical systems sometimes ya got to put a ground strap from the motor directly to yer earth ground” or some other such perl of wisdom.
@ruouttaurmind Watch it be just that. :B
Well @PooltoyWolf then you will just be blamed won’t you? Although come to think of it the blame for the A/C disaster is being shifted to you being that it is July and all. (smirk)
@Kidsandliz I didn’t do it, I swear -whistles out my valve-
@PooltoyWolf Did it or not… still your fault!
Honestly, at this point, if replacing the whole system was even a little economically feasible, I would be seriously considering it right now.
The repair company Dream Team arrived at about 8am. Spent maybe 45 minutes poking around, then knocked on the door with a revelation which they were 100% satisfied would cure my intermittent blower motor issue.
The system dataplate, which is well sun bleached and faded by nearly four decades of weather beyond readability) specifies a 1/3HP blower motor. But I replaced it with a 3/4HP blower motor.
I replaced the burned up motor, which ran perfectly for nearly 15 years, with an identical motor. But no worries. The motor I installed is multi-horsepower. Simply connect a different wire, swap out the capacitor with a different spec cap, and voila! 1/3HP blower motor.
Oddly enough, I had to point out to them the fact that this motor could be connected in 1/3HP mode. But I digress.
So once the system was up and running, everything seemed normal. But this is the pitfall of intermittent problems, innit. The techs buttoned up the system, confident they had finally resolved the problem.
Less than 10 minutes after they left, the first time the system cycled on… same old same old. The blower motor was running slow again.
They are convinced it’s a bad motor. This is the second motor which exhibits exactly the same problem. What are the odds two motors, from two different manufacturers, would have an identical intermittent failure?
Regardless, I told them to order a new motor and come back on Thursday afternoon to install it. But I also made it clear that I was dubious, and if this was not an ultimate solution I had no intention of paying for this new part.
So again… waiting for the next appointment and the next solution. Although they are not charging me for the additional service calls, I must draw this to a close. If they do not have a solution on Thursday afternoon, I’m moving on to another service provider. A different company may not have any more success, but at this point, the current company seems to be grasping at straws, just randomly replacing everything piece by piece.
@ruouttaurmind I’m really sorry that you’re having issues with your HVAC. Total bummer in the mid of summer
I would make a suggestion or two, but it sounds like everything has already been covered a half dozen times.
But I can’t help myself. Maybe it’s been discussed already, but I can’t be bothered to scroll through the mountain of replies here, so I’ll ask anyway. Have you checked the breakers? Both on the unit itself and in your electrical panel? I know it’s a long shot, but an intermittent problem could be caused by the breaker getting warm and failing.
@capguncowboy Thank you. At this point the pooches and myself have taken reasonable measures and it’s become more of an inconvenience than a crisis. A PITA inconvenience, but definitely a first world problem. The window AC has saved our bacon.
The breaker is holding solid contact and passing full current to the system. No buzzing or vibration at the breaker, and it stays cool; no overheating. That’s just about all the testing I know how to do for a 240VAC breaker. There is no breaker at the unit, only a pair of fuse packs.
Maybe the new contactor is burned up and when it arcs sometimes it makes contact and sometimes it doesn’t.
@cranky1950 The contractor nside the relay you mean?
@ruouttaurmind yeah, but then again if one leg is getting cut out a split phase motor should not spin at all. Did you replace the starting cap also?
@cranky1950 I replaced the cap, the service tech replaced the cap, and yesterday the team of technicians replaced the cap again. They also tried connecting to a different lead on the multi speed motor (medium high instead of high speed) because… at this point, why not?
I’m still thinking ground loop maybe? Intermittent ground loop, maybe feeding back through the 24v transformer which powers the relay actuators, causing intermittent poor current to motor or incomplete relay contact.
I’m thinking low voltage ground loop because occasionally when servicing the system I’ve experienced slight low voltage shocks when touching what should be neutral components. For example when touching the blower assembly chassis while also touching the primary power inlet conduit. I don’t know what effect this might have on proper motor operation, but at this point… nothing can be ruled out.
Another possibility might be a hairline fracture in the insulating Bakelite which supports the primary power buss? Maybe permitting an intermittent current bleed when the components heat up or cool down to some unknown level?
@ruouttaurmind
Have you tried replacing the cap?
@PlacidPenguin Um… “What is the most frequently asked question in this thread?”
/giphy Jeopardy
@PlacidPenguin @ruouttaurmind Check where ever a harness may rub, you might have worn insulation causing a flakey, Undo any cable clamps too. Check your ground electrode if the house is old and if you have not had rain for a while dump a buciet of water at the ground electrode. Is the rat race connected only to the motor ir is it one of those with the dual cage and bearings, the bearings may be siezing. Or, buy a 45 and go Elvis on it.
@ruouttaurmind
Are you asking me what it is, or are you telling me that the most common question is “What?” ?
@PlacidPenguin Phrasing my response in the form of a question so Alex Trebeck doesn’t belittle me for losing the game winning challenge?
Capacitor has been mentioned 49 times in this topic.
@cranky1950 I see your .45 and raise you a full auto Mac-10. Take it out in a blaze of glory.
When I was an electrical tech in the aircraft industry we used to have equipment which would fire 10kV through harnesses to expose minor or intermittent shorts and insulation flaws. That equipment would be useful right now. I’ve been through the wiring a few times looking for signs of wear or poor connections. I fixed a couple questionable terminal connectors, but nothing really obvious found. I need to look for ground faults or voltage leaks between conductors, but I don’t really have any tool to do that. Only so much I can accomplish with a Fluke meter.
The service company dream team returns Thursday afternoon with a new motor. I’m going to ask them to replace the transformer as well, just to eliminate any suspicion I have of a ground loop originating there. After that… it’s probably time to go Elvis on it’s ass.
@ruouttaurmind
Since when can you lose if you don’t phrase final Jeopardy response in a question form?
@narfcake
I SAID…
Since when can you lose if you don’t phrase final Jeopardy response in a question form?
@PlacidPenguin I don’t think that’s in Final Jeopardy though, only in in the Daily Double IIRC?
@PlacidPenguin @ruouttaurmind
@ruouttaurmind
Fair enough. I blame @pooltoywolf for the mix-up.
@PlacidPenguin @ruouttaurmind any answer not in the form of a question is invalid. For final jeopardy, there is a wager of points. If one has enough, or opponent has fewer points, one can still win final jeopardy with an answer not in the form of a question. Lose final jeopardy when you ain’t got enough points, darlin!
@ruouttaurmind good luck…we are dying in 98 degree heat … living room to room!
@mikibell @ruouttaurmind
Forgot to add the /s.
@mikibell Thanks! The outrageously overpriced window AC unit I picked up at Target last week is saving my bacon.
@PlacidPenguin I need a copy reader. Do you want to move to Arizona and work for peanuts?
@ruouttaurmind
I’ve never fried bacon.
How would it taste with a glazed peanut butter coating?
@ruouttaurmind @mfladd
Circus peanuts?
@PlacidPenguin Probably not delicious.
There’s a contractor team replacing the entire air conditioning unit for a neighbor today.
Started around 9am. On the 4th of July. In Texas.
@compunaut After watching the tech climb onto my roof that first day at 3:30PM when it was 108
outside and probably closer to 120
on the roof… I quickly gave up all the aspirations I never had of becoming a HVAC tech.
There’s a team of roofers stripping a neighbors roof on the next street this morning. So far outside my reality. Makes me wonder how I managed to do that kind of work when I was going to school.
@compunaut @ruouttaurmind I bet they get paid extra on holidays. Lots extra.
@compunaut @ruouttaurmind @sammydog01 My lawn care/landscaping crew worked this morning. We don’t have a set schedule, but I guess the grass didn’t know it was a holiday.
My commercial trash dumpsters were emptied today at about 5 AM. Trash doesn’t take a day off.
@therealjrn My trash guys certainly took off today. The township doesn’t do anything at all on holidays. I’m surprised the cops are even working.
@therealjrn Our trash guys don’t work holidays- they push collection back a day and fill in on Saturday. My daughter is flipping burgers today with no extra pay though.
@cinoclav @therealjrn @sammydog01
Surprisingly, the trash & recycling bins were emptied here today per normal schedule. They’re done by 10:30am tho, at least in my neighborhood.
@cinoclav @compunaut @sammydog01 @therealjrn
Recycling pickup in my area is done by a ‘private’ company, and they came today.
@compunaut Some of the subs were working on I-77 and I had to work if I wanted to get paid. The town grass cutting contractors were cuttring swales yesterday too.
@cinoclav The cops probably get bonus, on commission, ticket writing pay on holidays. That’s why they likely are working.
Latest update. The original service tech came back this afternoon. He told me the owner of the company basically pulled the plug on this project. They’re done trying to figure this out.
The justification offered: this system is over 35 years old and should be replaced. They’ve invested an inordinate effort attempting to resurrect a system which is well beyond it’s anticipated service life. They are happy to provide a competitive price to replace the system, but they won’t be doing any more work on this one.
Unfortunately he switched off the system while he was here, and now I can’t get the motor to restart again. Before, I could mess with it a bit and eventually it would spin up at full speed. Now… not.
Replacing the system is just not economically feasible right now. No way, no how.
So… ya.
@ruouttaurmind
So… You’re a worse position than before?
@PlacidPenguin True enough. Stuck with only the window unit which is struggling to do much good in the current 115 degree temp.
@ruouttaurmind
Maybe this will make you feel better:
My ideal temperature is roughly 72° F. Though with A/C, I’m slightly more tolerant.
@ruouttaurmind Why don’t you try wiring in a seperate circuit and let the motor just run like on cheep unit.
@cranky1950 That is my project for first thing in the morning. Bypass all electromechanical components and hotwire the blower directly into system power supply.
@cranky1950 @ruouttaurmind That’ll at least buy you some time and is exactly the route I’d go at this point
@ruouttaurmind
As it turns out, I’m not particularly well versed in the application of empathy or making people feel better.
@capguncowboy Time. Just a few more days so I can regroup and not make a panic decision in the throes of desperation.
@PlacidPenguin No worries. As it turns out, I’m not particularly susceptible to applications of empathy. So it’s all good.
@cranky1950
Easy peasy. One leg of the motor is already hard wired to the incoming power. The other goes through the 24v relay. When the ‘stat trips the relay, circuit closes. I just connected this lead to one of the unswitched “common” terminals on the relay. No cutting, no new wiring. Done and done.
Now I have the luxury of time to reassess and plan. I may even try replacing that transformer. It’s hot as hell and buzzes like a hornets nest. It’s about $10, so worth a shot if it’ll gain me another season from the system.
@cranky1950 @ruouttaurmind
/giphy cheering
@mikibell
It’s already down to a brisk 79 degrees in here! Was 92 when I woke up this morning. 
@ruouttaurmind Do you remember where your parka is?
@therealjrn Heh. I don’t recall ever owning such a piece of clothing. Though when I was staying in the UK I had a few heavy jackets. I could never warm up there.
@ruouttaurmind @therealjrn
Well duh. Owning winter equipment is not enough. You need to actually wear the stuff.
@PlacidPenguin @ruouttaurmind @therealjrn
As it turns out, I’m not particularly well versed in the application of empathy or making people feel better.
PlacidPenguin
Ah, I gotcha.
@HeadfoneJack @PlacidPenguin @ruouttaurmind
HVAC
The Final Chapter
Recap: The service company I was using gave up and told me the system was unrepairable and must be replaced. Quote was $6,000.
I fussed around with it after they left and got the blower running again. But it wasn’t performing reliably in “auto” mode. No worries, I set the thermostat to “on” and left the blower running 24/7.
A couple weeks later I ordered a few parts, and a new Honeywell wifi thermostat to replace the ‘stat that was fried as a result of the original motor failure. A 35 year old ‘stat I had on hand had been operating the system since I first replaced the blower motor just after the system went down at the end of June.
Two weeks ago I installed the new Honeywell ‘stat, a new 24 volt transformer and a new blower relay. I also ran a ground strap from the motor and the blower housing to the system chassis.
On my first test of the repairs the blower spun right up. Since then it has been functioning flawlessly in full automatic mode, everything working as designed.
No problems in 2 weeks, so I’m confident the situation has been resolved. I’m gonna call this one a win.
Thank goodness I didn’t give that service company the nod to replace the system! Not counting the new Honeywell ‘stat, I spent $19 and about 40 minutes replacing the parts. And saved myself $5981. Amen!
@ruouttaurmind I commend you for figuring that all out. I think I would of gone crazy on the journey you had.