Central AIR No Cool Air

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  #1  
Old 06-23-03, 03:21 PM
waybob
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Central AIR No Cool Air

I have a cen air unit Mfg CM, the fan will will turn on when I adjust the thermostat to cool and you can hear the compressor turn on for a couple of seconds( you can hear it humming) then it kicks out, I have checked the breaker inside the house and everything seems fine there. I checked the unit for a high limit reset and don't see anything on the unit. I have cleaned the inside of all debris and hosed out the metal fins. The unit came with the house and is probably around 10 years old, what else can I check to see where the problem or what the problem is
 
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  #2  
Old 06-23-03, 03:41 PM
bigjohn
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which fan comes on? The one in the outdoor unit, the indoor fan, or both? the compressor humming is usually one of 3 things:

1. Bad capacitor on the compressor motor- cheap

2. tight compressor for which the cure is booster starter- not too awful expensive.

3. Locked up compressor- $$$ With a unit 10 years old, the normal procedure would be to changeout the outdoor unit or the outdoor unit and a matching indoor coil. Several different things can cause a compressor failure and, they need to be investigated, otherwise the new one will fail.

Among the things that need checking are:

1. cleanliness or lack thereof of the indoor coil.

2. running the unit when it's low or out of refrigerant.

3. defective crankcase heater

4.improper refrigerant charge.

I hope you get lucky and it's just a bad capacitor or maybe you need the booster.
 
  #3  
Old 06-23-03, 04:08 PM
waybob
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cen air

I checked the unit again and there is a small gray cannister the size of a small oil filter with 2 leads one going to the contactor the other to the compressor, it looks like the one lead is blackened at the quick connect to the cannister, is this cannister the capacitor, there is also two capicators mounted above this, so I am not sure what this gray thing is. by the way both the inside and outsidde fans are turning on, Hiw can I check this capacitor to see if it is working or not
 
  #4  
Old 06-23-03, 04:20 PM
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Location: Massachusetts
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testing

without tools, you can't! There could be three capacitors. Run caps have a metal casing, are usually oblong, and have a rating written on them in the range of 5 to 88 uf (microfarads) 370 volt.
Start caps are usually a black plastic or bakalite type casing. good ones will have a resistor going across the terminals. easiest thing to do is replace the burt part and wiring, and see what happens. I don't think you'll be able to find a hard start booster, unless WW Grainger will sell you one. Start with the bad part first.
 
  #5  
Old 06-23-03, 04:22 PM
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Join Date: Nov 2002
Location: Massachusetts
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Oh ya...

Start caps are only in the circuit for a brief period and are in the range over 88uf
 
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