I looked at those connection in the return air, but only unpluged the multi plug going to the upper unit a couple of times. I did not unplug the six or so individual slide clamps from the thermostat. I will try that, however, when checking the thermostat, I was able to hear the relays clicking when flipped the thermostat fan switch and assumed they were ok. I probably need to do that again and get on top and see if 110 volts is getting to the motor.
2003 Ford F350 4X4 diesel drw cc; 2000 Lance 810 truck camper; hardly notice its back there. 2003 Jayco RKS 33, yes it is back there.