We have a Trane Voyager A/C unit that switches immediately from circuit #1 to circuit #2, even in test mode is will skip circuit #1. It is currently controlled by Alerton with a VLC that acts as the thermostat. When alerton is signaling for Comp #1, Comp. #2 is running, and when it signals for both compressors to run only comp 2 is on. Circuit #1 is larger than Circuit #2 so on hot days it cannot keep up with the demand. This unit also has an economizing feature (factory installed). Circuit #1 appears to be fully functional both LPS and HPS check out and when we jump circuit #1 to run its pressures are spot on. The LED indicators shows that everything is fine. Trane recommended replacement of the control board, but that did not help.

Does anyone know if there is some preinstalled logic on the control board that is trying to run the unit efficiently and ignoring the commands from alerton?