I've had an on going issue with my AC since December. Initially, it was intermittent hot/cold even when on max AC. Now it is just hot all the time. I've taken it to 2 dealerships and they've each started by telling me there is no issue. The first dealer eventually replaced 2 lines and recharged the system. The second said they can't find an issue and placed blame on the first dealer. They recharged the system (only 3 months after the first dealer did) and said it was working fine. I picked it up today, drove 5 minutes and it was warm the entire time, while on max AC. I drove back to the dealer and they said because the outside temp was below 40 degrees Fahrenheit, the compressor would not engage. Can anyone confirm this? I can't find any info confirming.

 

I can’t comment on the outside temp affecting the compressor, but if it was blowing cold and randomly would start blowing warm air, I would get the AC Switch checked. I had that issue on mine and the dealer found it as the problem. There would be times when I started the truck and it would just blow warm air with no AC, then 20 min later it would start blowing cold.

 

From the 2016 WSM:

NOTE: Compressor control and the evaporator temperature are a function of many parameters, not a straight on off to avoid freezing the evaporator. The PCM monitors multiple temperature sensors correlation (AAT, CHT, ECT IAT, MAF...) as applicable. The PCM runs this logic after an engine off and a calibrated soak period, typically 6 to 8 hours. This soak period allows the Ambient Air Temperature (AAT) sensor and the other temperature sensors to stabilize and not differ by greater than a calibrated value, typically 18ºC (32.4ºF). If a sensor input is found to be reporting a temperature imbalance the PCM does not allow the A/C clutch to engage. For more information on PCM sensors, Refer to Powertrain Control/Emissions Diagnosis (PC/ED) manual.

A/C Request

When an A/C request is received by the PCM, the A/C clutch relay is engaged when all of the following conditions
are met:

• Excessively high or low refrigerant pressure from the A/C pressure transducer is not detected.
• Ambient air temperature is above approximately 32.0°F (0°C).
• Evaporator temperature is above approximately 33.8°F (1°C).
• Engine coolant temperature conditions are within normal parameters.
• Wide Open Throttle (WOT) condition is not present.
• Engine torque conditions are within normal parameters.
• Battery state of charge conditions are within normal parameters.

Compressor control and the evaporator temperature are a function of many parameters, not just a straight on/off, to avoid freezing the evaporator. The PCM monitors multiple temperature sensors for correlation including, but not limited to, AAT, CACT, CHT, ECT, IAT, MAF, MAP, and MAPT (as applicable). The PCM runs this logic after an engine off and a calibrated soak period of 6 to 8 hours. This soak period allows the Ambient Air Temperature (AAT) sensor and the other temperature sensors to stabilize and not differ by greater than a calibrated value, typically 18ºC (32.4ºF). If a temperature sensor input is found to be reporting a temperature imbalance the PCM does not allow the A/C clutch to engage. For more information on PCM sensors, refer to Powertrain Control/Emissions Diagnosis (PC/ED) manual.

The PCM monitors the discharge pressure measured by the A/C pressure transducer. The PCM interrupts A/C compressor operation in the event the A/C pressure transducer indicates high system discharge pressures. It is also used to sense low charge conditions. If the pressure is below a predetermined value for a given ambient temperature, the PCM does not allow the A/C clutch to engage.