Trane Compressor Does Not Run, OD Fan Works, Air Handler Works


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Old 08-09-11, 08:04 PM
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Trane Compressor Does Not Run, OD Fan Works, Air Handler Works

11 year old Trane (American Standard) model TWR018C100A2 1.5 tons, compressor does not run, condenser fan does run, indoor air handler and thermostat work fine.

Already replaced the capacitor and added a start kit -- no help.

Pressed the contactor down with thermostat off and the fan came on, but no compressor. I have a new contactor and could replace it if you think it still may be a problem, although I did get 230V reading when pressed on both sides (24V, 2 Pole, 30 amp), and everything but the compressor does come on by itself with the thermostat calling.

The red light on the defrost control board blinks 29 times, then pauses and gives a double blink, then blinks 29 times again in a repeating cycle. Is this significant to a compressor not running? What does 29 blinks mean?

Any suggestions on my next steps?

Based on reading slightly similar posts, should I take ohm readings on the compressor? (if so, do I take the fan/top grill off and reach down between compressor and coils to hopefully see 3 wires and their connectors?) Is that also where I should try to look for any burnt wires?

I would really appreciate your expert help. I bolded my actual questions above. Thanks
 
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Old 08-10-11, 03:03 PM
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check the capacitor for swelling would be my first recommendation.
 
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Old 08-10-11, 04:47 PM
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Originally Posted by hvactechfw
check the capacitor for swelling would be my first recommendation.
He said that he already replaced the cap.

What is called for is to troubleshoot in a systematic manner, using the wiring schematic and a multimeter. Are you getting 240V to the compressor? If not, find out where it's being lost. If you are unsure how to do this safely, call in a recommended service person.
 
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Old 08-10-11, 06:06 PM
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Sorry.... missed that in the original post.
 
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Old 08-10-11, 06:36 PM
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Solved

UPDATE: Solved! It was the contactor after all. I had bought a new one, thought I tested the old (wrong!) so I didn't put it on. I had a wiring diagram and a good multimeter.

Some learnings I'll pass on:

1. I tested the compressor by first freeing 3 wires, which can all be done in the access panel. Orange unclips from the capacitor, red unscrews from the contactor, and the black w/blue stripe unscrews from the other side of the contactor. Once free, measure the ohms between the 3 wires. My readings were as follows, and my compressor is good:
:::Red to Black w/Blue stripe: 2.0 ohms
:::Orange to Black w/Blue stripe: 5.6 ohms
:::Red to Orange: 7.1 ohms (thought the 1st two would sum exactly to this one, but I guess close is good)

2. Capacitors can pack a punch RANDOMLY, and never forget that. In the capacitors I have changed, I have always shorted out the terminals after cutting all power. Tonight for the first time I've seen, the cap really sparked when I shorted the terminals (holding a plastic screwdriver handle). And this same capacitor in this same unit had not sparked before. I had almost become complacent...


I do have a question about something odd I see -- The black/blue wire going to the C terminal on the compressor is paired directly with the Line In black/blue wire, on the same side of the contactor. The terminal directly on the opposite side of the contactor is empty, without wires. This makes at least the one wire going to the compressor hot all of the time. Is this correct and by design, or did the original installer mis-wire the BK/BL wire at the contactor?

Thanks to gilmorrie and hvactechfw and all previous posters for assisting this DIY'er.
 
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Old 08-10-11, 08:03 PM
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Originally Posted by SeaDrive
I do have a question about something odd I see -- The black/blue wire going to the C terminal on the compressor is paired directly with the Line In black/blue wire, on the same side of the contactor. The terminal directly on the opposite side of the contactor is empty, without wires. This makes at least the one wire going to the compressor hot all of the time. Is this correct and by design, or did the original installer mis-wire the BK/BL wire at the contactor?
That is the way they were shipped from the factory. I tend to change the wiring so nothing is hot at all times when replacing the contactor. That is other than the crankcase heater if there is one.
 
 

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