I just repaced my mechanical thermostat with a hunter programmable one. The old t-stat had a high fan speed for A/C, and a low speed for heat. This new one only has high speed for both, though it goes to a low speed for cool down before it shuts off. The furnace had a fire in the fan wires shortly after making the change. I am concerened that it running on the higher speed caused this. I have completely redone the wiring in the furnace to the sechmatic in the service manual for this model and set-up, but it still runs the same. I am concerned about it starting on fire again. The old t-stat would not change temp,so the furnace would just run all the time.

I`d be surprised if you ever get it to working with a hunter tstat,, they are junk