I got a new circuit board and installed it myself using the wiring diagram - it was very straightforward, and I replaced the bad breaker. When I turned the system on it worked fine, except I could not turn it off at the thermostat.
After some investigation, I found that the thermostat had been completely re-wired, the red on the green, the green on the red and other problems. I suspect that was the result of a visitor to my lake place desperately trying to get the system working.
After I rewired the thermostat, the system works properly in terms of the low voltage controls sending out the right voltage on a specific setting, for example the fan comes on when the thermostat is set to " fan on". When you set the compressor to start by moving the control level on the thermostat below the actual temperature, the 24 volt control to the starter relay on the thermostat is activated - but the relay does not close. I have replaced the relay, but that did not solve the problem. I would expect that when the 24 volts gets to the relay terminal, the relay should close, even if it is not hooked up to the compressor, but that does not happen. I have the relay wired properly. I have a Coleman Air handler and a Trane 2.5 ton compressor.
Any help would be appreciated.