Sorry for the slow reply, I got busy and haven't got back to this. Thanks for the analysis Mark. Questions: 1) the fan does come on, just the compressor doesn't. Is your test (triggering pins 5,6, or 7 with +5V) still necessary? It seems that if the brain board is turning on the fan then +5V is going to the brain board which is the purpose of the test. 2) "...trigger pins 5 6 or 7 on THIS board using a jumper to +5v (pin 3 of CN14 or better yet the + of C3) to engage each relay separately..." On your labeled drawing above, pin 2 is +5V and pin 3 is +12V. Are we using 5 or 12V on pins 5, 6 and 7? I believe that's 5V and pin 2....or is it 12V and pin 3? In an earlier post it looks like I said the 12V regulator was 7812a. Seems like the other one was 7805 but I'm not at home at the moment. I can get a better pic of the top also. Really appreciate everyone's help. Humidity is bad and I've got an ancient 80s unit going that's on its last leg!