Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

The following conditions must be met in order for the ECM to turn on the compressor clutch:

Engine speed is greater than 600 RPM
Engine speed is less than 4, 760 RPM
A/C high side pressure is between 2957-151 kPa (22-429 psi)
Throttle position is less than 100 percent
Evaporator temperature is greater than 2°C (34°F)
ECM does not detect excessive torque load
ECM does not detect insufficient idle quality