AC trouble


  #1  
Old 05-08-12, 01:29 PM
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AC trouble

Hi guys, hope you could give me some advice.

Bought a house last July. AC is old but worked great last summer. No problems, Winter the heater worked great too. Had if off from about march till now, and now it seems the AC is having trouble.

When i turn first tried the AC, what im guessing is the compressor was having an issue with the thermostat and wasn't turning on.. the blower would run but no cold air. Turned it off for about 2 weeks, and tried it again. Now the (what im guessing from what ive read)is the compressor, seems to be turning on without trouble but it only stays on for about 3 minutes before it shuts off. The blower or fan keeps going

The compressor is making a different sound then it ever has before. When it turns on it seems louder, a lot lower pitched and seems to be vibrating a lot more violently. In the bathroom, the shower sliding glass doors chatter when it is on (its positioned on the roof over the bathroom) but obviously its vibrating more then it did last summer.

I have reset the breaker the AC is on but no change.
There is a high pitch buzz on the roof unit while the inside thermostat is set to off (dont know if that is normal)

What should i be looking for in symptoms or if this is an common problem.

Im relatively handy but want to know the most i can about the problem before i have someone come out ect. Ideas?

The brand is Carrier, but the specs plaque on the unit was too faded to get any info off.

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  #2  
Old 05-08-12, 02:11 PM
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The compressor seems to be trying to start but is unable to. The sound is different because it's not starting. They Will try to start until it gets too hot an shuts off. Might need a hard start or new capacitor.
 
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Old 05-08-12, 05:35 PM
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The coil probably needs cleaned in addition to what ender stated.
 
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Old 05-08-12, 09:55 PM
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Thanks for the advice.

Ender, when it does run for the first 3 minutes it is blowing cold air. Would what you said still apply if that is the case. and how would i do a hard start or check capacitor?

Also, is cleaning or checking the coil something i can do myself?

EDIT* with the replys i have looked and it looks like these are things i can do. I will give them a try and see what happens. Thanks. Any other advice will be appreciated .
 

Last edited by LeeLee12; 05-09-12 at 12:19 AM.
  #5  
Old 05-09-12, 07:12 AM
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If its blowing cold air those three minutes then I would say the compressor is running
 
  #6  
Old 05-09-12, 07:58 AM
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Here's a question from a Non-Pro....

You said the blower or fan continues to run....

Is that the air handler fan that actually moves air around the house? Or is it the fan that moves air across the condenser coils. Or both?


The reason I ask is that if the condenser fan is shutting off at the same time as the compressor...then that could indicate the contactor is opening up. If true...that, in combination with the buzzing sound you are hearing, could indicate a bad transformer that provides the voltage to close the contactor.

Transformers will normally hum a bit any time they have power applied, when they start to buzz loudly, it normally means they are failing.


I'm not sure if a weak transformer could cause the contactor to "chatter"....but if it did...that could affect the operation of the compressor also.
 
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Old 05-10-12, 01:30 PM
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So just checked something, When i turn on the AC it does the same, cold air blowing, but went up on the roof to look at the unit at the same time.. its sounds very "clunky" and the main fan on the unit (pictured below) is not spinning. The fan is not locked up, and spins easily.

so its the circulation fun that is continuing to run, the unit fan is not even spinning.

I have noticed that the cap to the motor of the fan seems to be melted. dont know if it was like this before or not. see pics below.

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Old 05-10-12, 01:50 PM
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Looks like the rain slinger melted due to a failed motor or capacitor. Check the capacitor in the electrical compartment in the unit on the roof.
 
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Old 05-10-12, 01:53 PM
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Well...can't see real well in the pic...but if that yellow gooey stuff is from a cap...yeah it needs replaced.

Personally...I'd probably replace the cap, fan motor and transformer. Less than $120 for parts most likely......

Cap first.......
 
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Old 05-10-12, 01:55 PM
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hvactech...whats a rainslinger? I have a package unit...don't know what you mean?
 
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Old 05-10-12, 01:57 PM
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Some old units used open cased motor and had a "rain slinger", or cap or hat that went over the motor shaft to keep rain and debris out of the motor. From what I can see in the picture that is what the OP is calling a cap.
 
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Old 05-10-12, 02:02 PM
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Thanks!............................
 
  #13  
Old 05-11-12, 06:53 AM
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Check the capacitor., They are cheap and easy to replace. Usually 3 terminals. Write down which color wires go to each terminal- usually HERM, com, and another.
 
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Old 05-28-12, 04:50 PM
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So I finally got around to doing some more work on the unit. I have fulled out the fan motor to get a better look and from the pictures below, im assuming the whole thing needs to be replaced all together.

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So while i shop for parts, i've been reading about capacitors, and wondering if i should just replace it while i'm up there or not. Its obviously been replaced before. See below. Would a bad capacitor do that to a fan motor (above) other causes?
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Old 05-28-12, 07:11 PM
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In regards to buying a new motor, I was able to get this info off the burnt label.

It was a
GE #5KCP39HG G399S 1-1.8 Amps, V 2.08-2.30 Hz 60 RPM 1125 1.PH
CAP 5.00/370

I have not been able to find that model or something identical too it but tons close. What should i be looking for in regards to a replacement and a capacitor to go with it.

Also because this is an outdoor exposed unit, I have been seeing terms like Open Drip and Totally Enclosed. Are those terms interchangeable and does that mean i can use that type?

Thanks again guys

Also, i have been looking locally for a supplier but any good online store people can recommend.
 
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Old 05-28-12, 11:14 PM
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any 1/4 horse condenser fan motor with an rpm above 1000 and 208-230 volts will do just fine. The newer motors cant handle as many amps and will probably be rated at 1.3 or 1.5 amps. single phase of course.
 
  #17  
Old 05-31-12, 07:59 PM
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Replaced the motor and cap today. Noticed that the previous motor was connected to two capacitors, one that i didnt notice before. (which matched the the specs with the new cap that i bought with new motor. so i replaced that one.)

Same problem as before. Compressor turns on (sounding very clunky), Condenser Fan still not starting. Tried to 'jump start' fan by pushing with no luck.

Im guessing that the Capacitor (pictured below) needs to be replaced as well.

Should i get one that matched the specs of the motor or the specs that is currently says on the old one?
 
  #18  
Old 06-01-12, 04:19 AM
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Can't see your pic. The cap must match new motor spec.
 
  #19  
Old 06-01-12, 10:05 AM
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Well im pretty bummed. Ive replaced the condenser fan motor, the Motor Cap and the Dual Run cap, and still nothing.

The fan wont start with any kind of jump start.


Any other ideas guys?
 
  #20  
Old 06-01-12, 11:30 AM
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You had to have hooked up the fan Motor incorrectly. The motor should have 4 wires. A black wire, a white wire, and two brown wires. Correct? The black wire goes to the top left of the contactor and the white wire goes to the top right of the contactor. The two brown wires go to a 5mf capacitor.
 
  #21  
Old 06-01-12, 12:07 PM
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the new one came with a Black, Purple, Brown and Brown/white

The original motor came with Black, Yellow, Brown and Red. (the red was just hanging in there with a wire nut on the end)

I connected:

Black to Black
Purple to Yellow
Browns to Run Cap
Brown/White to Run Cap

See Below

The Black does not go to the contractor (see start in bottom right end in top left)
Yellow goes to C on Dual Run CAP
Red from Run Cap running to C on Dual Run Cap

*i swear this was how it was hooked up. I took pictures and everything. It was running like this all last summer

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  #22  
Old 06-01-12, 12:29 PM
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I have to ask again...what do the transformer and contractor voltages look like? (didn't I ask before?)

A multimeter is vital for troubleshooting (though we know the motor and cap needed replaced). $10 for a cheapo that will do the job.

The transformer in the pic looks pretty rough.
 
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Old 06-01-12, 12:30 PM
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I see. The brown wires are supposed to go to each side of the 5 mf capacitor, not the same terminal. The red wire that you have hooked up to it was for the old motor, the new one does not need it. Remove the red wire that is connecting both capacitors.
 
  #24  
Old 06-01-12, 01:10 PM
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I really appreciate your guys help by the way.

So Ender i did what you said, and took off the red connecting wire and placed the brown wires on separate terminals.

With that done, when i flip the breaker, no power goes to AC. When i put them back and flip the breaker power come back to the unit. So for some reason, that is not working.

So im putting the wire back to the way it is in the picture for now, as so i can remember where things went.

Gunguy, im going to go test the voltages as soon as i put the wires back and have power to the unit
 
  #25  
Old 06-01-12, 01:17 PM
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Impossible. Don't worry about the voltage. Your voltages are normal. Sorry gun guy but we don't need to be checking for voltage. If the compressor is starting then it can't be a voltage problem. And you!!! If you want to put that wire back go ahead. But leave the browns on separate terminals. Also you, I installed 3 condenser fan motors today. And one was a heat pump. Just put the other wires to the contactor. Cut off the ends and screw them into it if you have to.
 
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Old 06-01-12, 01:51 PM
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This is supper annoying. So when i put everything back, either the way you told me too (regarding the red and brown wires) or what way it was before, when i flip the breaker back on, no power.

No power to the thermostat or hum on unit up top...

Soo im gonna break and have some food.

As for the contactor

Youre saying i should just connect the black wire form the motor directly to the contactor, where the compressor is attached,

And the Yellow, which is going to the Common on the Dual run Cap to the White on the contactor.

The two terminals under the word CAP on my picture.
 
 

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