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Time for a new meter and a T-stat.

Originally Posted by MIPAR

I checked a refrigerator compressor which according to the customer had been diagnosed as bad compressor and I found the following readings:
Run to Start: 2.2 ohm
Run to Common: .4 ohm
Start to Common: 2.1 ohm
I notice that 2.2 and 2.1 are very close could this be an indicative of a bad compressor? How could you diagnose this compressor based upon these readings?
Thank you

You are suppose to add common to start and common to run and add those numbers up which equals 2.5 ohms
Your reading for the start to run, which is the full winding, equals 2.2 ohms. The readings don't add up. There is a .3 ohm difference. The two readings should be equal.

Originally Posted by MIPAR

VTP99: I've heard a similar phrase " When in doubt, amp it out! "

The version I heard was "When in doubt, don't."

VTP99: I've heard a similar phrase " When in doubt, amp it out! "

The troubleshooting of this refrigerator was unplanned last night and it was kind of late so I didn't have time to troubleshoot more systematically, but I will possibly revisit this case during the week and also get the model number to provide it (I know it is a top-freezer Frigidaire refrigerator) I will trace the voltage to find out which component is cutting it out and hopefully the compressor will work once such component gets jumped out - -- will let you know the outcomes soon.

I've heard it said here " when in doubt jump it out "

Belt slipping on my comprehension level there, I apologize. I mis-read your Ohm-meter readings.

Originally Posted by Phase Loss

Sounds like the only thing wrong with your compressor is it doesn't have voltage.

Check your temp control!

Sounds like the only thing wrong with your compressor is it doesn't have voltage.

The 'Start' winding looks shorted. There should be more Ohms from C-to-S than from C-to-R. The Start winding should be 90-degrees out of phase with the Main winding in order to obtain turning torque and has to have more Ohms in it.

I would start by finding where you have voltage and tracing what is keeping it from the compressor. IE, make sure there is voltage entering the Unit then check the first control or switch it goes to, if that component is operating properly move to the next till you find the defective control. I would also jump the defective control out to ensure the compressor is not defective.

You did not mention the make / model of this refrigerator which would help in the diagnostics. It appears that you have a defective electical component that is preventing the compressor to start. First I would jump out the temp control followed by checking for voltage at the defrost timer, which by the way is not always present on refrigerators, then ohm out the relay.

I did not condemn the compressor either not only for the same reason sandshark mentioned, but primarily because the compressor was not receiving any voltage at all I even left the volt-meter connected to the two power lines on the back of the refrigerator while the owner was turning the timer clockwise with the screwdriver on the bottom front of the refrigerator because I was thinking that the refrigerator was probably on the defrost cycle and we heard the "click" sound several times, but the meter always read zero. It does not have any thermistors (temperature sensors) or mother board that could prevent voltage from reaching the compressor. Maybe it's the timer or the temperature control the problem What do you guys think?

Did you check anything else?

Start to run readings are very close to the sums of run to common and start to common, so I would not condemn the compressor based on those readings alone.

Questionable Compressor?

I checked a refrigerator compressor which according to the customer had been diagnosed as bad compressor and I found the following readings:
Run to Start: 2.2 ohm
Run to Common: .4 ohm
Start to Common: 2.1 ohm
I notice that 2.2 and 2.1 are very close could this be an indicative of a bad compressor? How could you diagnose this compressor based upon these readings?
Thank you