My actual model # is T3BA-042KA. The condenser does not appear to be receiving 24v at the relay. I don't know if that comes from the thermostat or via the air handler. I don't have wiring diagrams. Any ideas on what to check to troubleshoot this? If I manually press the relay down, the condenser starts up just fine. I have a new electronic thermostat - could that be the problem? It worked for a month, then the air handler fan would stay on even if the a/c cycled off. Is that a sticky relay or a bad thermostat? Could it be related to my current problem? thanks, paris