Maytag Performa PTB1953GEQ

[RogerB]

My fridge stopped cooling and was making the infamous clicking sound so I removed the start relay/cap from the compressor and tested the compressor, everything there looked good (R-S=12 ohms, R-C=5 ohms, S-C=7 ohms, also no shorts to ground for any of the pins).  So I got a 3 in 1 start relay and hooked it up but compressor still didn't start (used the RCO410).  Also had an RCO810 and tried it as well, nothing.  I put a current probe on the Run wire and it measured 9.5A, fairly close to the LRA of 10A stamped on the compressor label.  Current on the Start wire however was 0A, which seems puzzling since I measured 7 ohms S-C (and still did after removing the start relay and rechecking ohms).  I also tested the RCO410 unconnected from the compressor and both the Run and Start wires measured 120Vac relative to Common, but when installed on the compressor only the Run side measured 120Vac at turn on.  So it seems something odd with the Start winding with voltage?  I guess the compressor is probably locked but still like to understand the Start winding behavior if anyone knows.

[Hiroshi]

Did you wire the original thermal overload in with the URCO? (I always do) - but it sounds like you have the terminals reversed for start/ run for the URCO... because the start winding should get juice first, then the PTC should go infinite and route voltage to the run winding...

[RogerB]

Thanks Hiroshi.  I reversed Run and Start of the RCO and it did start up but then quit after 3-5 seconds or so.  I could see the Start current climb up to ~11A and then something in the compressor clicks and switches it off (thermal protection I guess).  If I cut power and repeat it does the same thing, so it's repeatable.  I did not wire the original thermal overload in only because I thought the RCO had one in it.  BTW, the original start relay assy had inputs labeled Line and Neutral (and different size blades so you couldn't mix them up), yet this RCO isn't labeled and says just connect them anyway you like.  Seems odd the old start relay assy was polarized but the RCO isn't? 

[RogerB]

I decided to hook up the old start relay/cap/overload and interestingly it now starts the compressor, but just like the 3 in 1 it clicks and quits running after 3-5 seconds.  Then after a minute or two tries again.  Click is from the compressor.  So it seems the old start relay assy was probably still good, but something in the compressor is wrong.  I think when I switched Run and Start above it unstuck the compressor so now it turns on with the old relay but something in the compressor prevents it from staying on.  So it seems like I have a bad compressor. 

[Hiroshi]

I agree, if a URCO can't keep it moving the compressor is toast, or soon will be. URCO's have the pin/terminal positions printed on the back of the sticker on the device, and they do have an overload built-in, but I believe it is an amperage based overload not a thermal one. I always used to leave the thermal overload on too, just in case, because folks tend to blame parts they can't understand- and I never take chances with safety in a customer's house! (i am no longer a field tech)

[RogerB]

Thanks again Hiroshi for your help, I'm feeling comfortable I have a compressor issue, such a pity as I was hoping to have one of those fridges that would last 25 years! :o)