I have a model 45t heater that is about 7 years old. I always keep it on minimum thermostat setting so the garage stays about 40f. It stopped working. I checked out the wall thermostat and power to the circuit board and all seems fine. I can get it to work normal by blowing a heat gun into the operation syster (circuit board, trans former, etc.) and it will continue to work fine as long as I have the heat setting at about 55f., below that it will not go on automatically. To get it to run again I repeat heating up the operating system for about 30 seconds and it will go on and run a full cycle
(fan, heat, etc.) but unless I turn the thermostat up to about 55f. it will not run again without me repeating the heating up process.