HVAC Outside Unit Buzzing - Fan Running Intermittently

Hi,

I've been combing this site for information, but I have a question I can't find an answer for.

Here's our situation -

  1. Last friday, we noticed the outside HVAC unit was making a loud humming/buzzing and the fan wasn't running.

  1. We turned it off & on from the inside of the house with no change. Buzzing stops when outside unit is off, indoor unit blows fine, the thin copper line was burning hot at the inside unit (didn't check the outside).

  2. Started looking here & saw the stick test. Fan moved freely with a stick, but we still didn't turn it back on for about an hour. In the meantime, my husband checked the fuses on the disconnect & called his HVAC buddy who seems to be on vacation.

  1. When we put the fuses back in the disconnect & turned it back on, everything started up fine & it ran good until sometime last night (today is Tuesday). We had a ton of ran dumped on us last Friday from a tropical storm & were hoping maybe something got flooded or something & we could make it until my husband's friend is available.

  2. So, today we left it off for about an hour, tried it & it still buzzed. Fan turns freely with a push. My husband went out to take off the access panel to pull the capacitor (all rusted up) to get a replacement & decided to pull the fuse & put it back on one more time just to see. Starts up like a charm.

He's going to get a new capacitor, new fuses & a new motor (just in case because with our luck it would run again until next friday night & go out for good in

100 degree heat) - but I can't understand why pulling those fuses & putting them back in does anything. Is it just coincidence that we finally let everything cool off enough?

The outside unit is probably close to 15 years old & the inside unit is the original with the house (from 1988) so we're due for a whole new setup, but I'd like to make it through the summer & have the replacement done in the spring or fall when the outdoor temps are more bearable.

Thanks in advance for your help

Reply to
shadow
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Where exactly in the unit is the buzzing coming from?

Reply to
recyclebinned

It maybe that there was corrosion buildup in the fuse or disconnect that yo ur husband "fixed" by removing and re-inserting it.

There are two major active components in the outside unit, a compressor and a fan. The compressor raises the refrigerant pressure which also concentr ates the heat. The refrigerant then gets circulated through the finned tub ing where the air from the fan cools it.

From your description it sounds like the compressor was running and the fan was not. The "buzzing" was probably the compressor. The fact that the sm all tube coming out of the unit was very hot also indicates that the compre ssor was running.

The compressor and fan are usually both turned on by on big relay, aka a co ntactor. The compressor and fan also both have capacitors or sometimes the y share what looks like one capacitor that really has two inside it.

I don't generally recommend troubleshooting by replacing parts but if you a re going to do that, the capacitor is the most likely suspect part and is a lso not very expensive. So I would try that first. The fan motor will be a bit pricer so I'd hold off on that. Most places will not take back elect rical parts.

Reply to
jamesgang

Those symptoms all point to a bad fan motor.

It sounds like coincidence. Sometimes with a failing motor, if you turn it, it may work again......for awhile. Forget about the capacitor. Even with the fan going, you reported that the pressure line was hot, so the buzzing must be the compressor. If the compressor was not running, you would not have a hot line. The cap is the starting cap for the compressor. The small motor for the fan, AFAIK, doesn't have a cap.

I would open it up enough so you can get a meter connected to the fan motor. If it has 240V and the fan ain't going, you've confirmed the problem.

From what I've heard so far, seems like you should be able to do that for the cost of a fan motor, which isn't that much.

Reply to
trader4

"shadow" wrote in message news:52d3$51b745c3$45499b77$ snipped-for-privacy@news.flashnewsgroups.com...

The buzzing could be comming from a relay that controls the fan. It may be going bad.

Reply to
Ralph Mowery

Single phase motors are not self starting, they have an extra winding with a capacitor in series ans sometimes a centrifugal switch. It sounds like the start winding/circuit has some sort of intermittant connection. There is info here but you need some technical knowledge to understand it.

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Reply to
harry

I'm not sure - it sounds like the whole thing is buzzing & we didn't want to power it up with the access panels off. That's a lot of electricity coming through there.

However, we've had problems with the inside motor doing the same thing - bad capacitor or motor seized - and it makes about the same sound.

We just switched out the capacitor & turned it back on - big copper pipe at the air handler already has condensation on it, small pipe is about room temp.

Only problem is that we have no idea if it's fixed or not since pulling the quick disconnect outside & reinserting it seems to reset something. Any ideas on that? It doesn't make any sense to me.

Reply to
shadow

OMG, run and hide under the bed!! If running an AC with the cover off is so frightning, time to call a pro.

Reply to
trader4

your husband "fixed" by removing and re-inserting it.

No because from orignal post, only the fan was not running. There was "buzzing" and the pressure side line at the air hander was hot.

nd a fan.  The compressor raises the refrigerant pressure which also conc entrates the heat.  The refrigerant then gets circulated through the finn ed tubing where the air from the fan cools it.

No shit sherlock, so why the diversion into corrosion at the dsconnect?

 The "buzzing" was probably the compressor.  The fact that the small tube coming out of the unit was very hot also indicates that the compressor was running.

See above.

contactor.  The compressor and fan also both have capacitors or sometimes they share what looks like one capacitor that really has two inside it.

are going to do that, the capacitor is the most likely suspect part and is also not very expensive.  So I would try that first.  The fan motor wi ll be a bit pricer so I'd hold off on that.  Most places will not take ba ck electrical parts.- Hide quoted text -

The capacitor? The freaking fan that is the most likely suspect doesn't have a cap. Good grief!

Reply to
trader4

But more likely, the "buzz" is the compressor running

Reply to
trader4

replying to harry , shadow wrote: Thanks for all the input. Sorry for starting a few arguments.

Our fan motor uses a dual run capacitor. It was all rusty with something that looked like it could have been a leak to one side. Could also have been just corrosion on the outside too - hard to say. The unit is at least 13 years old & we've owned the house for 8 years - it's probably all the original parts because we haven't had any problems with the outside unit until now. (Yes, I know we're due for an entire replacement - would like to make it until fall when the temperatures are more comfortable)

I agree that it could also be the fan motor - bought a new one just in case. Anything more than that, we'll wait for our HVAC friend to get back.

But I'm not ruling out the capacitor alone - on Friday, it was definitely just the fan not working because the return line was so hot. This morning, I don't think the compressor was running either because the line was room temp. To me, that would mean that either the capacitor didn't kick on the compressor or the compressor overheated & shut off. Again, I'm not a pro.

I was mostly curious about why pulling the disconnect was necessary to make things start working again. The fuses are old - I bet they're the originals - but they look OK. None of the copper on either the fuses or the connections looks corroded or anything.

Reply to
shadow

Remember. It's not a joke, or a dare or a thrill Buzzed air conditioning is broken air conditioning. Call a pro before you get busted. . Christopher A. Young Learn more about Jesus

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. . wrote in message news: snipped-for-privacy@googlegroups.com... Where exactly in the unit is the buzzing coming from?

Reply to
Stormin Mormon

The buzzing could be comming from a relay that controls the fan. It may be going bad.

Reply to
Stormin Mormon

replying to harry , shadow wrote: Thanks for the input.

Our fan is wired to a dual run capacitor - I agree it could be the fan motor itself, so we bought one just in case. Never hurts to have spare parts laying around.

I've been reading about the relays & other things that it could be. Anything more complicated than the capacitor or fan motor probably means we'll wait for my husband's HVAC pro friend to get back in town.

The capacitor looked awful - rusted to the point you couldn't read the labeling. The unit is 13+ years old & we've owned the house for 8 years without needing to make any repairs. I'd bet it was the original part.

I know what the compressor sounds like when it's running - the buzz/hum was much louder & somewhat different from that. Sounded more like what happened when the capacitor went bad in our air handler.

As for corrosion in the fuses, the fuses & the relay hardware looks nice, clean & shiny - although the fuses look pretty old. Our HVAC store didn't sell those, so we'll buy somewhere else or order.

We probably just need to replace the entire thing since the outdoor unit is over

13 years old and the inside unit is about 25 years old, but it would be nice to do it in the fall when the temps are lower.
Reply to
shadow

replying to shadow, shadow wrote: Sorry for the somewhat double post - It took a really long time for my original response to show up.

Reply to
shadow

I am about to have a similar problem. Where can I buy the capacitor?

Reply to
Chuck

ou are going to do that, the capacitor is the most likely suspect part and is also not very expensive.  So I would try that first.  The fan motor will be a bit pricer so I'd hold off on that.  Most places will not take back electrical parts.- Hide quoted text -

trader, you usually give out good info but in this case I'm not so sure...

the fan motor in my AC definitely does have a running cap so at least SOME units do have caps for the fan.. neither of us have any way of knowing specifically about the OPs unit...

OP, can you tell use the make and model number of your AC?

Mark

Reply to
Mark

I am about to have a similar problem. Where can I buy the capacitor?

Reply to
Stormin Mormon

t your husband "fixed" by removing and re-inserting it.

and a fan.  The compressor raises the refrigerant pressure which also co ncentrates the heat.  The refrigerant then gets circulated through the fi nned tubing where the air from the fan cools it.

fan was not.

a contactor.  The compressor and fan also both have capacitors or sometim es they share what looks like one capacitor that really has two inside it.

ou are going to do that, the capacitor is the most likely suspect part and is also not very expensive.  So I would try that first.  The fan motor will be a bit pricer so I'd hold off on that.  Most places will not take back electrical parts.- Hide quoted text -

I suggest you do your research a little more carefully. 99% of outdoor uni ts have a dual cap that is for both the fan and the compressor. It may be that you didn't realize the cap was really two caps but if you look at the wiring you will see differently.

Reply to
jamesgang

Glad it's working out for you. Hopefully that will take care of you for a while.

The buzz may have been from the fan motor since you are pretty sure it was different from the compressor. The fan motor will still be getting power e ven though the cap is bad. The dual cap is a common failing item on outsid e units and is easily the cheapest part to try. I would have held off on b uying the spare motor since they are so easy to get but to each his own. T he only other significant part outside is the contactor (big fat relay) but when it fails nothing will be running.

Most of the compressors do have internal thermal protection and if overheat ing for some reason will cycle on and off as that protect kicks in and then the unit cools down.

I you replace it this fall you will most likely be getting the new refriger ant. R410 or "puron" as one company calls it. It will run at a higher pre ssure. I think school is still out on new equipment service life.

Reply to
jamesgang

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