Compressor Troubleshooting Help


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Old 08-09-11, 07:08 PM
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Compressor Troubleshooting Help

My father in-law has a Nordyne/Miller self contained unit that is not working. The compressor and fan are not coming on. Changed the run cap still no worky. The contactor is pulling in, but when I check the voltage across the compressor contacts I get 0V. I can get the fan to run but have to disconnect the feed wire to the run cap. Resistance across the red/blk wires for compressor was very close to zero 0.7 Ohms. My thought is it's the compressor, but wanted to make sure I'm not missing something????

Thanx
 
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Old 08-10-11, 03:06 PM
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how many volts into the contactor and how many out?
 
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Old 08-10-11, 07:00 PM
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Originally Posted by hvactechfw
how many volts into the contactor and how many out?
It was around 220V in, but nothing out. If I disconnect the compressor wires it will go to 220V out???
 
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Old 08-10-11, 07:40 PM
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Originally Posted by johnboy68
It was around 220V in, but nothing out. If I disconnect the compressor wires it will go to 220V out???
This makes no sense. You either have voltage coming out of the contactor or you dont.
 
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Old 08-10-11, 07:41 PM
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that doesn't make any sense. Check each leg to ground. In and out of contactor.
 
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Old 08-11-11, 04:52 AM
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So from leg to leg I had nothing, if I went from each leg to ground it was 115V on both sides of the contactor.

I measured the resistance between the two legs and it was just about 0 Ohms, I would have thought this would trip the breaker????

The more I think about it, has to be the compressor, we replaced the run cap, but not sure if it was replaced with the right rating (couldn't read the reading on old one). If it wasn't shouldn't the unit still run???? The old run cap was not bulged at all, but outside was rusty.......

Thanx
 
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Old 08-12-11, 04:55 PM
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you have to have resistance between the 3 terminals any mix with the wires disconnected then go to the copper pipe with one lead and check each terminal should be 00.0 looking for windings grounded like holding the leads together reading or audible... the contactor is one contact if you read both sides inn and out YES you will read 0volts need to read the disconnect coming in to contactor then to other 208/230 single phase....check for power ot of the disconnect then follow it in...
 
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Old 08-12-11, 04:56 PM
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I think you have a fuse out on one leg. Look for fuses in the disconnect and remove them and check their resistance. what you are seeing when checking each leg to ground is one leg going through the load ( compressor or fan motor) and showing up on the other side where checking it. If it were the compressor the fan motor would run. The fan motor is not running which is indicating low or no voltage. Or it is miswired. Another thing is that you have not mentioned that you hear the compressor or fan motor making noise but not starting. This is what you would expect if they were receiving power. If there are no fuses in the disconnect then you may have a bad breaker with only one leg connecting.
 
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Old 08-22-11, 05:56 PM
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Originally Posted by hvactechfw
I think you have a fuse out on one leg. Look for fuses in the disconnect and remove them and check their resistance. what you are seeing when checking each leg to ground is one leg going through the load ( compressor or fan motor) and showing up on the other side where checking it. If it were the compressor the fan motor would run. The fan motor is not running which is indicating low or no voltage. Or it is miswired. Another thing is that you have not mentioned that you hear the compressor or fan motor making noise but not starting. This is what you would expect if they were receiving power. If there are no fuses in the disconnect then you may have a bad breaker with only one leg connecting.
You were correct I was missing the voltage...... I only checked continuity through one of the contactor legs. The other leg was not a direct short, cleaned it now back in business didn't pay much attention to the contactor as it's only a few months old???

Thanks to everone for the help
 
 

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