This is great information. Thanks. It is definitely tied into the cabin temperature. I parked my car in a sunny location for 4 hours last Sunday. The outdoor air temperature was in the 22F range although; the cabin was probably in the mid 70's. I was in manual mode set in the mixed (air out of the panel vents and floor vents) setting. The manual temperature settings were set at 67 F and the compressor was engaging.