I just bought a modular home in April and it came with a Honeywell thermostat. At increasingly frequent intervals, warm air will start blowing out of the vents and it smells like the furnace is on. It will run for 15-20 minutes and heats the house up by at least 5 degrees. It will occasionally stop if I turn off the unit, but sometimes it starts blowing hot air as soon as I turn it back on again. There doesn't seem to be a set pattern to when it happens. It can happen anytime day or night. Sometimes it is right as the AC turns off and then it will heat up enough for the AC to need to turn back on. The general handy man from the company who built the home is sending out an HVAC guy tomorrow because he cannot figure it out. Any ideas as to what he will tell me? Thank you so much!