I have a MiniMax Plus 400 heater that is dying on me.
It was working so-so last year, and when I tried to start it for the first time this year I just did not even hear the igniter running.
I opened the service door, and noticed that a (transistor?) at the Thermostat Circuit Board TCB was missing, and some other components were a bit 'toasted'. So I replaced the whole board.
Then, I tried to start the heater with the brand new TCB. I could hear the igniter, and I can see the pilot is ON. All of the heater lights (other than the "HEATER") are on, both outside and inside.
So, trying to troubleshoot the Pilot module, I checked voltage between the blue and white wires and while doing it the heater starts!
It runs for 15 minutes. I turn it off and then on again and it does not start. I can hear the igniter and the pilot is ON but the heater does not start. I checked voltages again and the thing starts! So, I tried it for a third time and now the heater does not start at all. Pilot ON, igniter running, but heater is off.
Is it the pilot module? the gas valve?