Help! My problem started with the compressor not running with the heat switch on. I checked the thermostat wiring and found that the tstat was not wired per the manual for a heat pump with aux heat. I fixed that problem and the unit would run but not blow warm air. I called out a technician and he said I needed a new tstat and a defrost board. Also note that after the tech left the unit will not do anything! I can't even get the fan to run. Since then I've replaced the defrost board, contactor, outside breaker, and tstat. (The outside breaker needed replaced because one pole was only putting out 8 volts.) All my wires between the tstat and unit are good (continuity check) I have 240V coming in to the unit -- NO 24V from transformer-- but the coils test OK? When I push in the contactor no operation of any thing. Are there any safety switches or something else that's tripped that would cause all components not to work? I have a payne PH1ZNA030000AAAA heat pump.

Call the tech back. You should have had them fix to start with then it would be there responsibility to get it running correctly. You may have thought you saved a few $$ but actually now you will spend more$$.

Check for a fuse on control voltage. Easy enough to blow while you are checking things.