why is my GMC Sierra AC blowing warm air when set to cold

Complete guide to fixing AC that blows warm air in GMC Sierra. Includes symptoms, diagnostic steps, tools required, and repair procedures.

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface and the engine is off.
• Disconnect the battery for safety.

2. Check and Recharge Refrigerant

• Tools Required: Refrigerant gauge set, refrigerant canister.
• Connect the refrigerant gauge set to the low-pressure service port.
• Check the pressure readings; if low, add refrigerant according to the manufacturer’s specifications.
• Monitor the system for any leaks during the process.

3. Inspect AC Compressor

• Tools Required: Socket set, multimeter.
• Locate the AC compressor and visually inspect for any damage or signs of leaks.
• Use a multimeter to check the electrical connections at the compressor.
• If the compressor does not engage, check the fuses and relays associated with the AC system.

4. Replace Cabin Air Filter

• Tools Required: None typically needed, but a flathead screwdriver may be necessary for some models.
• Locate the cabin air filter housing, usually under the dashboard or in the engine compartment.
• Remove the cover and take out the old filter.
• Insert a new cabin air filter, ensuring it is oriented correctly.

5. Test and Replace Blend Door Actuator (if necessary)

• Tools Required: Torx or socket set.
• Remove the dashboard panel to access the blend door actuator.
• Disconnect the actuator and test it with a multimeter for proper operation.
• If faulty, replace it with a new actuator and reassemble the dashboard.