Quote:
Originally Posted by Buckeyexx
Sorry didn’t mention the model. It’s a passport 239ml. The air conditioner is not heat and cool both just cool.
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If you have a digital thermostat, when you turn the thermostat to heat and the fan to HI or LO, the air conditioner fan will come on when the furnace fan comes on and go off when the furnace fan turns off. The intent is to increase circulation of the warm air by using the A/C fan to increase airflow. The digital thermostat controls the furnace "through the HVAC control box located in the air conditioner return air plenum.
It (the HVAC control box has nothing to do with whether your air conditioner is "cool only", "heat pump" or "heat strip augmented"... Nearly all the air conditioners with a digital thermostat have the HVAC control box.
Added: If you remove the filter, you will probably see one of these boxes mounted in the return air chamber. The gray one is the "old style HVAC control box" the silver one is the "new style HVAC control box". I'd almost bet you have one, it's damaged, and you don't even know it's there... Few people do, so don't think anything about missing it.....