Outside AC Unit Issue: Feedback Appreciated

TimC24601

Hello. I am having an issue with my AC unit. When I set my thermostat to cool, the unit kicks on like it normally would, the fan in the unit starts up, and we begin to get cool air in the house like we expect to. However, after running for 20 - 45 minutes, the fan in the unit stops. When this happens, the unit appears to be attempting to run still as it is making a buzzing noise. If I turn the AC off for a while and then back on, it starts back up normally, but then repeats the issue after 20-45 minutes of running. Does anyone have any idea of what the issue here might be?

Thanks,
Tim

Harvey Ramer

More likely than not, you have bad bearings in the condenser fan motor. Once the unit has been running for a while, does the motor getting piping hot? Careful you don't burn yourself! If so you will likely need to replace the fan motor.

It could also be pitted contacts in the contactor that turns on the compressor and fan motor. Pitted contacts cause a poor connection, restricting the flow of electricity and causing motors to overheat and trip on thermal. That would be the first thing to check but past experience would indicate bad bearings to be the more likely culprit.

Whatever you do, get it taken care of right away before it causes compressor damage due to elevated head pressures resulting from decreased air flow through the condenser.

TimC24601

Harvey,

Thank You for the prompt feedback. I went outside to give some of the piping a feel. One line did feel pretty warm, bordering on hot. I have attached a picture with an arrow indicating which line I'm referring to. Does this particular line being warm/hot match with what your thoughts were?

Thanks,
Tim

Harvey Ramer

Sorry, not talking about the piping. Does the fan motor get hot?

GW

He probably can't get his hands or fingers on the fan motor.

Yes, piping hot was just an expression.

So does the outside ac unit still make a low pitch humming sound when the fan stops spinning, or, does everything go silent? In other words I'm asking if the compressor is still running or not. The compressor sounds like a super heavy duty refrigerator, a deep moaning/humming sound.

The buzzing noise, please give me a comparison, is it like a cheap men's shaver slightly muffled? Or more robust like what I described above?

Gary

TimC24601

Gary,

Thanks for the input. During the issue I've described, the AC unit continues to make the more robust noise you mentioned. Also, you were correct in stating that I'm unable to feel the motor in order to gauge the heat it's giving off.

Thanks,
Tim

GW

Tim, sounds like it is indeed the fan motor. If you're handy it is not the worst do-it-yourself job, getting the fan blade off may be a royal pain in the rump.

GW

Also Tim, yes that pipe will be hot for sure if your fan motor croaked.

I suspect this is an R22 system, and not a "newer" R410a system. Normally the small pipe will be very roughly and very unofficially 20 degress warmer than the outdoor air temp. When the fan stops cooling off the condenser coil, the hot refrigerant will be very hot, too hot to touch.

If it's by chance an R410a system, it's very roughly 3 to 10 degress warmer than the outdoor air.

Like mentioned, don't keep running your system, unless of course you're thinking of a total system replacement.

Harvey Ramer

And before you order a new motor, attempt to remove the fan from the motor shaft. If you cannot remove the fan, you'll have to get a new one of them as well.

TimC24601

Harvey and Gary,

Thank You both. I believe I am handy enough to replace the motor; last year I replaced the furnace motor after watching a YouTube video. Per Harvey's suggestion, I will first attempt to remove the fan from the motor shaft.

Thanks Again to Both of You,
Tim

GW

Yes we simply order the fan and blade togeter. Once we determine a bad motor we pack up and leave, we don't start pulling things apart for a 20 dollar part (or whatever they cost).

Best of luck!

Gary

Harvey Ramer

Gary your method is probably more efficient but I just hate throwing away good parts.

JUGHNE

Fan motors can quit because of a failing run capacitor. Might start slow and run on low speed, overheat and then stop on overload. Restart after cool down.

Because of this very problem one homeowner was told they needed a complete change out. (That didn't happen).
It was a combo cap and both motors eventually were overheating and no start.

Whatever it is, you want it corrected or you will be looking at a complete change out. IMO

GW

Harvey, yes either way is good, but we both know a stuck blade can eat some time. I don't pull blades enough to be a "blade pulling expert" just like I'm not an expert at many clunky and outdated things.

Yes I didn't mention the capacitor, they are super cheap, get a new cap too.

JUGHNE

I pull blades because I may have the motor & cap on the shelf. But a new blade is at least 1 day or more away. If the blade comes off I wash it and check for loose rivets and hairline cracks.

I do have the official puller but have found that removing any set screws, soaking with Kroil or PB and then insert open end wrenches between blade and motor. Add enough wrenches to almost cover the exposed shaft. Then pry down on 2 of the wrenches that are located 180 degrees apart, this will usually push the blade up without hammering on the shaft which will mushroom the end and require filing down. Just a Red Green approach one learns in the outback.

GW

Good idea, I will have to try that someday

Steamhead

JUGHNE said:

Just a Red Green approach one learns in the outback.

Can't be one of his unless there's duct tape involved

Tinman

Sand the motor shaft sparkling clean, spray some WD40 on it, tighten an adjustable wrench to the flat of the shaft and turn the blade, using the wrench as a backup. Most of the time that frees up the blade without the need for a puller.

JUGHNE

Yes, that will work also. If the motor is not maybe 20 years old.
The duct tape is still close for repairing cuts to the hands during this adventure......so the Red Green legacy continues.

I mentioned that WD-40 smells too good to be effective, nasty PB blaster or Kroil tells you that something will come apart.

Tinman

I should clarify. I should have said frame of the blade. I have an insane amount of stitches but none by using this method

JUGHNE

Really good duct tape will eliminate the need for those stiches.

GreenGene

.......and once again you people give away your knowledge for free

if you call the auto shop do they give DIY's all their knowledge or say "bring it in"

if you call the dentist do they tell you how to DIY?


I just feel at times we're giving away our years of knowledge, rarely do we say

you need to call a pro

Harvey Ramer

Giving away knowledge for free pays 10 fold. You become the guy that knows things and you will have plenty of work always.

That has been my experience.

ChrisJ

GreenGene said:

.......and once again you people give away your knowledge for free

if you call the auto shop do they give DIY's all their knowledge or say "bring it in"

if you call the dentist do they tell you how to DIY?


I just feel at times we're giving away our years of knowledge, rarely do we say

you need to call a pro

Why are you on a forum?

This is the entire point of a public forum. Communication.
"Giving away your knowledge for free" in hopes to benefit others.

JUGHNE

This person would probably try the repair anyway. It is better he asks questions here....he could become the victim HO I mentioned above with the bad 10 dollar capacitor who was told he needs a complete new system. I believe the OP knows his limitations, I and many others here have told some posters our best guess of their problem and that they need a pro. Then those who follow that advice with some idea of the problem will at least have a chance to avoid the big salesman.

Years ago people were able to fix some things themselves. Today I notice some who cannot reset a circuit breaker, if they have an old fuse box they are really lost. Changing a spark plug in the lawnmower would be a major challenge. All goes back to things like the now long gone high school shop class etc....etc.

Of course some DIY adventures go south. This makes the HO appreciate the pro trades even more. Some ask me to do some simple plumbing repairs, and I try to talk them thru it but they say they tried one time and had a bad experience.
Saw a plumber with the hat that said "I can repair anything your husband just 'fixed' "

I have over 40 years in all trades mentioned on this site including electrical. Almost every day on the wall lets me come away with more free knowledge than I had before.
I would venture that applies to all who visit here on a regular basis.
With every bit of advice given here to the DIY by one of us, we get perhaps 3 more ideas as a solution, some better some not.

GW

the beauty of a 1st world nation, I think most of get out what we put in.

sure, some more and some less.

for many, it's hard to identify the 'I should stop now, I'm over my head' line in the sand.

If i stopped every time i didn't know what to do next, I'd be in different line of work for sure.

Techman

The 1st test that I would have performed on the cond fan motor is the "spin,look,listen,feel"test. If it is the bearings the shaft/fan blade will slow down quickly,or you can hear and feel for a grinding/noisy bearing. The the 2nd thing that I would have done is replacing of the run cap and running and amp testing.

I also do the two adjustable under the fan hub and pry trick. I also carry three "auto ball joint "tools. I also use the Kroil spray rust-bust fluid,when I do at 1st condemn a motor.I also agree w/ Harvey about reusing the "still good" cond fan blade. It just takes more skill/knowledge/practice to be able to re-use that blade/pulley. Its easy to replace motor/blade all/every time, less skillful.

AMservices

Some Motors I work on have built-in thermal overloads, that open when the motor gets too hot and close once it cools down.
Take a look at your condensing coil, if it's dirty, clean it.
If it's clean and the problem still occurs, change the motor and the capacitor as a precautionary measure.
Try to get a direct replacement motor so you don't have to worry about the C.W.- C.C.W.
Give the blade a shot of PB "Blast", let it sit for 30 minutes, if the set screw doesn't come out or you think your about to get hurt, it's not worth it, just get a new blade.

One more thing, PLEASE DO NOT! Use this information to start an HVAC company. There's just not enough work for everyone

aircooled81

I think it's great everyone pitches in with some words of wisdom. I've changed a few condensor fan motors in my time, but I liked the post about stacking the wrenches instead of a puller. And breaking the fan loose by spinning the blade on the shaft,
I sure learned a few cool ideas. As I always seem to do hanging out with the Wallies

Don't worry about a homeowner replacing a condenser fan motor or capacitor, there are still plenty others out there who will pay for that service.

JUGHNE

The ball joint tool I had was loaned out about 20 years ago, but that is the concept of the tapered open end wrenches.
Also sometimes there is a ring of rust where the shaft leaves the hub. If severe I use a deep socket to tap the hub a little farther onto the shaft and file the ring away, then back to the other methods for removal.
Laying the old blade on a flat surface will reveal any bent wings, I do it for both sides.
For this poster, if you reuse your old blade, check for loose rivets and cracks in each wing of the blade.

Techman

x2,jungh! Also,I clean up the shaft before taping the blade down that little bit.