Trane XV 90 won't heat. Fan runs, but just recirculates the (cold) air. I checked the covers on the unit -- they are in contact with the pressure switch. Brrr. Thermostat set to 68; inside temp is 59.

It should have a blinking light on the control board to tell you what's wrong(lower blower door). You can turn the power off and back on to the furnace to reset the control board to let it try and work again. If something major is wrong it will not light.

Trane XV 90 won't heat. Fan runs, but just recirculates the (cold) air. I checked the covers on the unit -- they are in contact with the pressure switch. Brrr. Thermostat set to 68; inside temp is 59.
Red LED flashes 4 times -- "Hi Limit Switch". I have shut off all electricity to the appliance after setting thermostat down to lowest setting (40). Waited 5 minutes - restarted --- same result.

Reaffirmed what I had found -- but I was not sure if I was missing something