A Radiothermostat CT80 fails to signal heatpump cooling, so jumpering the RED node with the GRN (Fan) and YEL (Cooling) node has successfully enabled cooling.

The weather became cold, so the thermostat must have switched the reversing valve to enable heat. When the the RED node with the GRN (Fan) and YEL node, heat is measured at the HVAC register.


Is it now warm and humid. I believe that the valve needs to be reversed to enable cooling? The potential across the BLU (Common) and ORANGE is negligeable, whereas the BLU-RED is 28V AC. Is reversing the valve a simple matter of jumpering the RED to the ORANGE wire for 2-3 seconds?

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