Have an 17 year old Trane XE 80 and recently the heat comes on and then the fan will not stop blowing after heating up to the temp indicated on the thermostat.

Model # is TUD080C936H4. Trouble code is 5 flashes which according to the manual is: "flame sensed with gas valve off" .

Have read a few similar problems but not this model. I had a licensed HVAC company come in 3 days ago and do a clean/checkup of the unit prior to winter and was told everything checked out. This problem had never occurred before until their visit. They came highly recommended.

What should I be looking at to try and fix this? They won't come back out without charging me again.

I will also mention that if I try to turn the unit off at the thermostat - nothing happens. Normally we would hear a "click" at the thermostat when the unit goes on or off - but that doesn't happen now...