Looking for A/C troubleshoot help

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workingovertime
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Looking for A/C troubleshoot help

Post by workingovertime »

A/C suddenly stopped right when putting the baby to sleep on a Memorial Day. Talk about timing! Of course no one here will even pick up for an emergency service on a Memorial Dat afternoon. Don't blame them!

Hoping somone here can point to the right direction. We have 2 distinct signs:
1) AC fan outside squealing with no movement
2) Central AC unit inside the house continues to run indefinitely even when thermostat is set OFF. Could be thermostat wiring issue?

Just weird that there seems to be issues at 2 different places that both started suddenly. I'm thinking it has to be related. Just can't seem to pinpoint it.
shunkman
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Re: Looking for A/C troubleshoot help

Post by shunkman »

Outdoor fan motor is fried. Thermostat wiring rarely goes bad unless something melted it. Shut the entire system off using the breaker or safety switch and wait for emergency service.
tibbitts
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Re: Looking for A/C troubleshoot help

Post by tibbitts »

workingovertime wrote: Mon May 31, 2021 7:02 pm A/C suddenly stopped right when putting the baby to sleep on a Memorial Day. Talk about timing! Of course no one here will even pick up for an emergency service on a Memorial Dat afternoon. Don't blame them!

Hoping somone here can point to the right direction. We have 2 distinct signs:
1) AC fan outside squealing with no movement
2) Central AC unit inside the house continues to run indefinitely even when thermostat is set OFF. Could be thermostat wiring issue?

Just weird that there seems to be issues at 2 different places that both started suddenly. I'm thinking it has to be related. Just can't seem to pinpoint it.
If the outside fan doesn't run at all, I don't think that's related to the thermostat. It sounds like there's a physical problem with the fan motor/bearings. Inside is anybody's guess. How hot is it? Do you need service today? Actually the timing is extremely favorable: mine always went out on first night of a holiday weekend with temperatures at least in the 90s.
suemarkp
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Re: Looking for A/C troubleshoot help

Post by suemarkp »

I would hope a thermostat setting of OFF would turn off the fan, but it may not. The OFF-HEAT-COOL-AUTO controls commands to the furnace and AC to turn on. The Fan AUTO-ON tells the fan to either be controlled by the heater or AC unit, or to run continuously. Look to see if the fan AUTO-ON is set to on. Running the inside fan may be beneficial, as it will at least circulate air through the ductwork. It won't be cooled though.

The outside fan could be just a bad capacitor on the fan motor so it won't start. One of the cheapest things to fix and doesn't require opening the coolant lines. I would turn of the outside disconnect to the AC unit so it doesn't try to keep starting the fan which could damage it (it should be thermally protected which will shut it up for a while but then it will try to start again until the thermal protector opens again).
Mark | Somewhere in WA State
carolinaman
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Re: Looking for A/C troubleshoot help

Post by carolinaman »

shunkman wrote: Mon May 31, 2021 7:19 pm Outdoor fan motor is fried. Thermostat wiring rarely goes bad unless something melted it. Shut the entire system off using the breaker or safety switch and wait for emergency service.
+1. I agree. This has happened to us a couple of times. When fan is not working, the cool air cannot get distributed thru the house.
helwardman
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Re: Looking for A/C troubleshoot help

Post by helwardman »

Definitely sounds like the capacitor is faulty on the outside unit. THE most common A/C fault. Easy fix and not too expensive.
tev9876
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Re: Looking for A/C troubleshoot help

Post by tev9876 »

Another vote for the starter capacitor. One way to check is to push a small stick through the grate when the fan is trying to run to give the blade a push. If it keeps spinning, even if not full speed, it is an indication the motor is working but the capacitor has failed preventing the initial rotation. Mine died last year, of course on a 95 degree Sunday.

It is a very easy fix if you are comfortable working on basic electrical stuff. It is really just a few sheet metal screws to remove the cover, remove the capacitor clamp, swap out push on electrical terminals and reassemble. 100s of videos on Youtube can walk you through it.

You won't find a replacement capacitor at a big box store. I don't know if AC contractors will sell you one without a service call. You can get them on Amazon and other online sources, but that can take several days. Check Grainger - they are the 7/11 of the industrial world with many local locations stocking replacement parts, but not as cheap as online. Once you pull the old one and can get the microfarad and voltage ratings along with the physical size/shape you can look it up on their website and hopefully find one nearby. Think mine was $15 and I was at the Grainger about a mile from my house as soon as they opened Monday morning. Was back up and running five minutes after I got home.
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lthenderson
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Re: Looking for A/C troubleshoot help

Post by lthenderson »

workingovertime wrote: Mon May 31, 2021 7:02 pm 2) Central AC unit inside the house continues to run indefinitely even when thermostat is set OFF. Could be thermostat wiring issue?
I agree with others above about your first question. I'm guessing for this question, you are referring to your fan inside is still pushing air through the ducts even with the thermostat off. Many thermostats allow you to still run the fan to circulate air even when no heat or cool air is being introduced. I would look through your fan settings on your thermostat to see if this is the case.
sk2101
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Re: Looking for A/C troubleshoot help

Post by sk2101 »

helwardman wrote: Tue Jun 01, 2021 7:19 am Definitely sounds like the capacitor is faulty on the outside unit. THE most common A/C fault. Easy fix and not too expensive.
Agree. I always have a spare capacitor on hand for these kind of situations. I recommend everytone to do the same, as they are cheap, easy to replace and sometimes it is not easy to find the exact model you need. Amazon is a good source.
bluegill
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Re: Looking for A/C troubleshoot help

Post by bluegill »

A very common problem with AC is the condenser/capacitor is worn out/defective. Worn out capacitor will cause the motor to not start, but it will probably hum. Capacitor costs around $10 on Amazon. AC contractor will charge you $150-$200. It is easy to replace. Size: cylinder, around 2" diameter, 4 " long, 3 wires, behind sheet metal. AC high voltage is dangerous.
sycamore
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Re: Looking for A/C troubleshoot help

Post by sycamore »

bluegill wrote: Wed Jun 02, 2021 7:58 am A very common problem with AC is the condenser/capacitor is worn out/defective. Worn out capacitor will cause the motor to not start, but it will probably hum. Capacitor costs around $10 on Amazon. AC contractor will charge you $150-$200. It is easy to replace. Size: cylinder, around 2" diameter, 4 " long, 3 wires, behind sheet metal. AC high voltage is dangerous.
Agree it's a common problem. I've also seen a problem a mouse getting inside and building a nest by the capacitor. The mouse got fried, and so did the capacitor. I've also heard that insects/ants could cause the same problem.

Does the OP's symptom "AC fan outside squealing with no movement" jibe with a worn out capacitor? With a worn-out capacitor, would you even hear the fan make a noise?
phxjcc
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Re: Looking for A/C troubleshoot help

Post by phxjcc »

Wanted to add:

There are two capacitors--start and run.

Always have spares of each.

For some reason my unit goes through them once a year.

It is a five minute job to replace them--one wire at a time.

PLEASE BE SURE TO PULL THE FUSEABLE LINK BEFORE WORKING ON THE UNIT---small metal box, it may be near the unit or the Circuit Breaker Panel.

Good luck.

...and yes, the fan will run with the temp over the set temp on the thermostat because the thermostat has "told" the compressor to start and there is no feedback loop to the fan control to tell it that the compressor is not running.
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Harry Livermore
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Re: Looking for A/C troubleshoot help

Post by Harry Livermore »

+1 on the capacitor... in fact, this just happened to us 2 weeks ago. Not on a "service plan" so it ended up being 2 service calls because they had one cap on the truck but needed to order the other one and come back.
When the fan failed to work originally I also suspected the fan motor. The cheap paper sticker had worn and peeled away so I had not idea what model it was... and they are pretty specific. And Carrier won't tell a consumer.
Luckily the tech who came out hooked me up with that info.
Good idea to keep spare caps for the next time. I will do that.
Cheers
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Abe
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Re: Looking for A/C troubleshoot help

Post by Abe »

tev9876 wrote: Tue Jun 01, 2021 8:12 am Another vote for the starter capacitor. One way to check is to push a small stick through the grate when the fan is trying to run to give the blade a push. If it keeps spinning, even if not full speed, it is an indication the motor is working but the capacitor has failed preventing the initial rotation. Mine died last year, of course on a 95 degree Sunday.

It is a very easy fix if you are comfortable working on basic electrical stuff. It is really just a few sheet metal screws to remove the cover, remove the capacitor clamp, swap out push on electrical terminals and reassemble. 100s of videos on Youtube can walk you through it.

You won't find a replacement capacitor at a big box store. I don't know if AC contractors will sell you one without a service call. You can get them on Amazon and other online sources, but that can take several days. Check Grainger - they are the 7/11 of the industrial world with many local locations stocking replacement parts, but not as cheap as online. Once you pull the old one and can get the microfarad and voltage ratings along with the physical size/shape you can look it up on their website and hopefully find one nearby. Think mine was $15 and I was at the Grainger about a mile from my house as soon as they opened Monday morning. Was back up and running five minutes after I got home.
I agree with the above. It very well may be the start capacitor. The capacitor helps the fan motor start. If you give the fan blade a push and it starts running then it's probably a bad capacitor. As others have said, they are cheap and fairly easy to install. If the fan motor starts running when you give the blade a push, you can set your thermostat to fan (not auto) and the fan motor should continue running until you can replace the capacitor.
Slow and steady wins the race.
rich126
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Re: Looking for A/C troubleshoot help

Post by rich126 »

helwardman wrote: Tue Jun 01, 2021 7:19 am Definitely sounds like the capacitor is faulty on the outside unit. THE most common A/C fault. Easy fix and not too expensive.
In my last house I had a very old AC. It was old prior to me moving in and I did nothing to service it since I figured it would be money down the drain. One day it stopped working. I called someone that I kind of knew from years earlier. Turned out just a capacitor and was an easy fix.
Kagord
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Re: Looking for A/C troubleshoot help

Post by Kagord »

phxjcc wrote: Wed Jun 02, 2021 11:51 am
There are two capacitors--start and run.

Always have spares of each.
Thank you, mine had 3 capacitors, a fan, compressor run and compressor start, and I ordered all three after seeing this thread, even though my AC was blowing 63 out the vents. I tried to get locally, HVAC distributors adamantly will not sell to the public and are quite rude about that when you ask, I've run into this before at plumbing ones too. I got on Amazon, no prime options so it took 4-5 days to get them, I would not want to be down for this time if there was an issue.

As luck would have it, my AC stopped working last night, the compressor wasn't turning on. I opened the back panel, the compressor start capacitor had swelled and had nasty ooze stuff on it, and failed on my multimeter uf test. Took 10 minutes to replace, and it's working again. So 6 or so days after I received the parts, I needed one of them.

Thanks again, $80 in parts on hand isa lot cheaper than a service call and perhaps days quicker to service, I doubt a service company would have this on the truck, so more costs there as well.
iamblessed
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Re: Looking for A/C troubleshoot help

Post by iamblessed »

tev9876 wrote: Tue Jun 01, 2021 8:12 am Another vote for the starter capacitor. One way to check is to push a small stick through the grate when the fan is trying to run to give the blade a push. If it keeps spinning, even if not full speed, it is an indication the motor is working but the capacitor has failed preventing the initial rotation. Mine died last year, of course on a 95 degree Sunday.

It is a very easy fix if you are comfortable working on basic electrical stuff. It is really just a few sheet metal screws to remove the cover, remove the capacitor clamp, swap out push on electrical terminals and reassemble. 100s of videos on Youtube can walk you through it.

You won't find a replacement capacitor at a big box store. I don't know if AC contractors will sell you one without a service call. You can get them on Amazon and other online sources, but that can take several days. Check Grainger - they are the 7/11 of the industrial world with many local locations stocking replacement parts, but not as cheap as online. Once you pull the old one and can get the microfarad and voltage ratings along with the physical size/shape you can look it up on their website and hopefully find one nearby. Think mine was $15 and I was at the Grainger about a mile from my house as soon as they opened Monday morning. Was back up and running five minutes after I got home.
Yeah sounds like a capacitor. If the one on the inside goes out it can smell to. That how I knew. The long stick idea is good just keep you hands far away from the fan. I got stuck in the middle of winter. Grainger was closed that day. I started it with a long piece of wood until I could make it to Grainger. I think it was something like a $10 fix.
neilpilot
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Re: Looking for A/C troubleshoot help

Post by neilpilot »

workingovertime wrote: Mon May 31, 2021 7:02 pm A/C suddenly stopped right when putting the baby to sleep on a Memorial Day. Talk about timing! Of course no one here will even pick up for an emergency service on a Memorial Dat afternoon. Don't blame them!
Workingovertime - Shouldn't you provide an update?
Kagord wrote: Mon Jun 14, 2021 11:59 am
As luck would have it, my AC stopped working last night, the compressor wasn't turning on. I opened the back panel, the compressor start capacitor had swelled and had nasty ooze stuff on it, and failed on my multimeter uf test. Took 10 minutes to replace, and it's working again. So 6 or so days after I received the parts, I needed one of them.
Kagord - If the capacitor has swelled, even if it's not leaking, just replace it. There's no need to test the old capacitor, since it's obviously gone.
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TexasPE
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Re: Looking for A/C troubleshoot help

Post by TexasPE »

sk2101 wrote: Tue Jun 01, 2021 9:25 am
helwardman wrote: Tue Jun 01, 2021 7:19 am Definitely sounds like the capacitor is faulty on the outside unit. THE most common A/C fault. Easy fix and not too expensive.
Agree. I always have a spare capacitor on hand for these kind of situations. I recommend everytone to do the same, as they are cheap, easy to replace and sometimes it is not easy to find the exact model you need. Amazon is a good source.
Thanks for the prompt - just finished ordering two exact replacement capacitors for my two systems for $30, including shipping! In SE TX, the AC gets a workout (upper 90s today).
At 20: I cared what everyone thought about me | At 40: I didn't give a damn what anyone thought of me | Now that I'm 60: I realize that no one was really thinking about me at all | Winston Churchill (?)
acegolfer
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Re: Looking for A/C troubleshoot help

Post by acegolfer »

sk2101 wrote: Tue Jun 01, 2021 9:25 am Agree. I always have a spare capacitor on hand for these kind of situations. I recommend everytone to do the same, as they are cheap, easy to replace and sometimes it is not easy to find the exact model you need. Amazon is a good source.
It's a good idea to have a spare. But 2 things to note: (1) A typical A/C capacitor life expectancy is 10-20 years. Even if we use A/C every day in S. Florida, mine just failed after 8 years. (2) Capacity has a shelf life. After 10 years, it not really a brand new.

Instead of having a spare that you may not need for the next 10 years, it may be better to know where you can get a capacitor locally fast.
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TexasPE
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Re: Looking for A/C troubleshoot help

Post by TexasPE »

acegolfer wrote: Wed Jun 16, 2021 12:01 pm
Instead of having a spare that you may not need for the next 10 years, it may be better to know where you can get a capacitor locally fast.
In my area, suppliers are open 40 hours/ week. They charge ~4x the internet price if they have the capacitor in stock. (Some don't sell retail). I have to call around to find what I need. They may not have a direct replacement so mounting can be a problem. My brother lives in a rural area and can't quickly pick up a capacitor.

IMHO spending $15 for an identical replacement capacitor to have on hand that can be installed in 10-minutes nights, holidays and weekends is cheap insurance- YMMV.
At 20: I cared what everyone thought about me | At 40: I didn't give a damn what anyone thought of me | Now that I'm 60: I realize that no one was really thinking about me at all | Winston Churchill (?)
acegolfer
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Re: Looking for A/C troubleshoot help

Post by acegolfer »

TexasPE wrote: Wed Jun 16, 2021 7:06 pm
acegolfer wrote: Wed Jun 16, 2021 12:01 pm
Instead of having a spare that you may not need for the next 10 years, it may be better to know where you can get a capacitor locally fast.
In my area, suppliers are open 40 hours/ week. They charge ~4x the internet price if they have the capacitor in stock. (Some don't sell retail). I have to call around to find what I need. They may not have a direct replacement so mounting can be a problem. My brother lives in a rural area and can't quickly pick up a capacitor.

IMHO spending $15 for an identical replacement capacitor to have on hand that can be installed in 10-minutes nights, holidays and weekends is cheap insurance- YMMV.
Agreed. If I couldn't get a replacement for cheap fast, I'd keep a spare.
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