Truck Trend Garage: 2007 Denalis Air Conditioning Doesnt Work
Question: My 2007 Denali's air conditioning doesn't work at all, but the seats still cool. What could cause that?
| Truck Trend Garage A Bunch Of Hot Air
Answer: The seat heat/cool function and the passenger compartment climate control are two totally independent systems. The seats use a separate climate-control module and driver within the seat cushion and seatback to electrically heat and cool them with the use of a heating grid and ventilation system. The passenger compartment uses a true air-conditioning system with R134a refrigerant circulated through the compressor, condenser, expansion valve, and evaporator to produce high-performance cooling.
Is the air coming out of the ducts warm, or is it not blowing at all? The answer will narrow down the list of possible causes. If there's no air at all, you're looking at the blower motor and blower control circuits. If it's blowing warm air, that usually leans toward a mechanical failure of the refrigerant system, typically a refrigerant leak. But more things can go wrong with today's more complex climate-control systems. There could be a mode door actuator deflecting air through the heater core, as opposed to the A/C evaporator. Seeing that it's a late-model American full-size, I'd suggest getting it to a GMC service department for your best chance for an accurate diagnosis the first time.
Can't wait for help with a problem you're having with your Truck or SUV? Ask the expert we trust here at Truck Trend Garage -- visit Alex Steele at www.RealWorldAutomotive.com.
