I have a GE 25,000 BTU window unit that is 11 years old. I turned it on for the first time of the season today and it ran perfect until this evening, when it didn't restart and just hums. I shut it off and checked the breaker to see if one leg popped and it didn't. I haven't checked the voltage at the plug yet to be sure it is getting 220 but I assume it is.
Is this most likely the compressor and should I consider getting it fixed or just buy a new one? Anything else to check?
Thanks for the help!
BTW I am no piker do-it-yourselfer. I can fix about anything.
You don't mention which is humming.. The compressor, or the fan
motor..? If the fan working, but it is the compressor humming, it
could be a bad cap. A cap shouldn't cost anywhere close to $100
if you go buy the part somewhere.
You can sort of test a cap with a VOM set to resistance.
First, short the cap terminals together.. Then apply the leads across
the cap and look for a quick indication of resistance which quickly
falls off to nothing. That is the voltage from the meter charging the
cap. You don't want to see a constant dead short, or always open.
That won't tell you if the value is correct, but will let you know if it's
open, shorted, or otherwise acting as normal. They have digital cap
testers that can read the value, but it's really not needed for what
you are doing. The tool could cost more than the part to fix the
A/C if it's something cheap and simple like a cap.
Most units use a "dual" cap which is used for both the fan motor,
and the compressor.
If the fan motor is humming, and no air is blowing, it could also be a cap,
but often is a bad fan motor.
In many cases, you will have the fan motor go out. Often they get
hot and go off on internal overload. So then you have the compressor
running, but the head pressure is going through the roof due to no fan,
and before long, it too overheats and goes off on internal overload.
It will reset once it cools down if this happens. The only thing is,
when it compressor goes off on overload, it will not make a sound.
No humming at all until the overload cools off and reconnects
the circuit. A compressor that hums either is having trouble starting
due to a bad cap, not equalized yet, or could even be a bad compressor.
Some get "tight" and hard to start and require a start kit to get going.
You can buy ones that are single piece and look like a stick of TNT..
You just connect it in parallel with the stock cap for the compressor.
Look at the cap. The top where the terminals are should be perfectly
flat and level. If the top is bulged out a bit, it's likely shorted internally
and is likely bad. I see this quite often these days with all the cheap
caps they use these days. Yep, make sure you really have 220v at
the socket.
A 25k BTU window unit is pretty good sized and not cheap to replace
so it could be worth fixing unless the compressor is shot.
If it had a bad fan motor, I would probably fix it. Course, it doesn't
cost me a lot to change a motor.. I don't charge myself labor.. :/
(or dies in this case).
