[Richard]

Hi Glenn,

You would have the SCS basement units from the year coach and your description.

So that I don’t make any wrong assumptions in trying to help you. Can you provide some specificity about what you did?

Did you add external relays for the compressors?
Did you replace the relays on the boards for the fans?
Would you disconnect the GL1 and GL2 wires from the back of the thermostat? It is quick and easy, and will eliminate any potential internal issues with the Tstat.

Would you post pics of the control board please.

Nice work BTW. I like the preventative care. I did the same. My wife does NOT like to be hot.

If you got the neutral and the hots reversed on the fan motor, it could be making a circuit from hot to ground and bypassing the relay altogether.

If you replaced the relays on the board, some solder could have inadvertently bridged a circuit.
The relay could be welded shut.