Our rear A.C. unit was not producing cold air. The fan would come on but the compressor would not. Since we have multiple of the same A.C. units, we could easily swap components to see which one was failing.
This is the capacitor, one of the components we swapped to see what was failing.
Another component we swapped between two A.C. units was a control unit. If you do this, be sure to pay attention to the positions of the DIP switches (if yours has any).
This is the top of the compressor with the PTCR attached (also known as a "termistor").
PTCR - Positive Temperature Coefficient Resistor
When we removed the cover to these wires, it was pretty obvious that the end of the brown wire (which looks good here) was fried off (see image below).
If we had started here, we would have found the failure right away. LOL. But, we wouldn't have had all the fun, I mean "learning experience", of swapping components.
An image of the entire PTCR that fried, failed, and prevented the A.C. unit compressor from coming on.
This is the fried end of the PTCR. If you look at one of the images of a good PTCR, you can see the clear insulation on the brown wire that is supposed to be on this one. Totally burned off.
When attaching the male end of the blade connection to this female end, make sure you don't inadvertently put the blade between the insulation and the female connector. That could cause a bad electrical connection. Make sure the male part is fully inside the female part.
As of this writing, a new one costs about $40.
A side-by-side of the old and new PTCR.
Here's the YouTube video explaining what we did.
This is one of the many YouTube videos that we found that talked about diagnosing A.C. units. This one, in particular, had a lot of good technical data and hands-on testing with a multi-meter.
