Monday ordered the HVAC module and it arrived today. It took all of 15 minutes to R/R the module and test the system. These are the results: Dual mode working normally. Ran control functions and temperature settings and now system cools and heats as expected. Success! The original HVAC module was part of the 8.4 UAQ upgrade kit and dual zone option. The first modification to the system was configured as a single zone ATC system all worked well. When I changed the hardware and settings to a dual zone system my adventure began. Electrical components can fail without any indication as evidenced by the “new” module failure.