Long Battle with AC/Furnace/Heat Pump Issues

burgess001 wrote:
I'm old school too. I was convinced it was the main board that drives both AC's, both Heat Pumps, and the Furnace. Reason was, when it got cold enough to kick the heat pumps over to furnace, nothing worked. That was just too much of a coincidence. I'm guessing the wire was keeping the rear heat pump (which was not on) from telling the furnace it could come on. Its too much for me. I can't do anything but air the tires any more.

1. There is NO main board that controls all those functions
2. That "phone wire" is a communication cable that links the front AC to the Rear AC and the wall tstat. There is a "Phone" cable from the wall tstat to the front AC. There is a "Phone" cable from the front AC to the Rear AC
3. The wall tstat on your Dometic system DOES communicate with BOTH Roof AC Module boards. But the tstat ONLY sees what the Roof AC boards tell it to see.
4. When the outside Ambient temp gets too cold for the HP to produce heat (below 35 degrees), on EACH HP, there is an outside ambient temp thermistor and when it senses below 35 degrees, the Control board for THAT HP will stop the compressor and activate the furnace automatically. IF you have just 1 furnace, then the Rear HP will just stop running and the front HP (which the furnace is wired to) will activate the furnace as long as the front HP has also sensed that 35 degree ambient temp. If you have 2 furnaces, then the rear furnace will be activated by the rear HP and the front furnace will be activated by the front HP
5. Regardless, when you have such a intermittent problem as this, you need to have the Service Technician be aware of all the previous repairs that have not fixed the problem. Doug