compressor not working

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Old 04-19-11, 02:59 PM
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compressor not working

I have a Trane model TTJ730A100B0. The fan on the outside unit runs but the compressor does not seem to run. However, it draws 3.3 amps when the fan comes on. The R.L. amp rating is 17.1. I replaced the run capacitor, but that did not fix the problem. There is high voltage to the S and R terminals of the compressor, and when the fan comes on there is 110 volts at the other terminal. When the fan is not running the compressor does not draw any current. I do not have gauges, so I do not know the pressures.
 
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Old 04-19-11, 05:02 PM
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sounds like the compressor may be done for. you would need to remove the wires from the compressor and check for shorts to ground and check the resistance of the windings across each other, S to R, R to C, and S to C.
 
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Old 04-19-11, 05:18 PM
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thanks

Thank you. I will check those resistances. Is it also possible I could be low on freon and the compressor has an internal pressure switch?
 
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Old 04-19-11, 05:25 PM
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A ttj is a very old a/c and would only have a internal thermal overload circuit and not a pressure circuit. if you touch the casing of the compressor and it is very hot then run water on the compressor to hopefully reset the overload circuit.
 
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Old 04-19-11, 06:00 PM
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I got the following resistance readings:
S to R is 4.4 ohms,
R to C is inf,
R to S is inf,
R to ground is inf,
S to ground is inf,
C to ground is inf
The compressor does not get hot when it is supposed to be running.
 
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Old 04-19-11, 06:06 PM
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you wrote S to R is 4.4 and R to S is inf. which one is it? Are you checking these at the terminals on the compressor or through the wiring? Should be checking at the compressor terminals
 
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Old 04-19-11, 06:11 PM
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S to R is 4.4 ohms,
R to C is inf,
C to S is inf,’
R to ground is inf,
S to ground is inf,
C to ground is inf
checked at the compressor terminals
 
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Old 04-19-11, 06:18 PM
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IF I am correct, the thermal overload has tripped because it is typically on C (common) Its been a while since Ive seen this so, I may be wrong. If I am wrong then the compressor windings are open and the compressor is toast. If I'm right you can smack the compressor with a board (sometimes this will work, but not very often) and it may close the overload circuit. IF the board trick works then get a tech out to look over the system and check the charge.
 
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Old 04-20-11, 06:03 AM
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I smacked the compressor good, and now it is running. But, it does not cool very well. I can feel the condenser coils getting warm, but not hot. I will now call a tech to check the charge. I really appreciate your help.
 
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Old 04-20-11, 06:15 AM
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no problem,wait to you see my bill!
 
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Old 04-20-11, 03:07 PM
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overload could have been tripped when you checked resistance. but you said it wasnt hot. it could be on its way out, overload went off for a reason. keep an eye on it
 
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Old 05-30-11, 07:07 PM
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I've got the same problem...I guess I'll start by replacing the Run Capacitor first also...Ugh....Hopefully the Compressor isn't shot.
 
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