Lenox heater whisper 20 series blower motor will not work when placed on aoto but will operate when placed in the ON position

It could be ANYTHING from a bad thermostat, loose wire, temperature switch, control board, or any of a dozen things and I can only recommend a tech to go through the PROCESS of checking your electronic components.

We know the motor is OK. The relay is working so I would check the fan control switch. Could be a thermostat but they usually fail all the way. Not sure if there is a separate switch or if it in the control board.

Probably a stupid answer. But On works no mater what the temp is. Auto Comes on when Heat or Cool is selected And temperature is set to operate?

When set to Cool, Does Compressor Kick in?