In my 21bhe, my thermostat has the following modes to include fan, cool low, cool high, cool auto and heat. Cool auto cycles the blower on and off with the AC compressor. Cool low and cool high maintain a continuous blower operation as the compressor cycles on and off based on temperature. I am after that constant background noise that the continuous running of the fan provides as well as keep more even heat distribution through increased air circulation. Short of installing another thermostat to force the roof unit to run the fan continuous, has anyone been able to mod the furnace to provide continuous fan operation in spite of furnace cycling on and off?