GMC Sierra T1XX (2019-Present) AC not blowing cold air, how to fix?

GMC Sierra T1XX (2019-Present)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

3 min read

538 words

Problem Statement

Learn how to diagnose and fix AC not blowing cold air in GMC Sierra T1XX. Step-by-step guide with diagnostic procedures and repair instructions.

Affected Component

HVAC

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow the engine to cool before inspecting AC components.

Symptoms

•AC blows warm air instead of cold
•Decreased airflow from the vents
•Unusual noises from the AC compressor
•AC compressor not engaging
•Increased humidity inside the cabin

Diagnostic Steps

1
Check the AC system pressure using a manifold gauge set.
2
Inspect the AC compressor for signs of damage or leaks.
3
Verify the operation of the AC clutch by checking for engagement.
4
Examine the cabin air filter for blockages affecting airflow.
5
Scan the vehicle's computer for any diagnostic trouble codes (DTCs) related to the AC system.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•Manifold gauge set
•Socket set
•Screwdrivers
•Safety glasses
•Gloves

Parts Required

•Refrigerant (R-134a)
•AC compressor (if faulty)
•Cabin air filter (if dirty)

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Diagnostic Steps

1
Check the AC system pressure using a manifold gauge set.
2
Inspect the AC compressor for signs of damage or leaks.
3
Verify the operation of the AC clutch by checking for engagement.
4
Examine the cabin air filter for blockages affecting airflow.
5
Scan the vehicle's computer for any diagnostic trouble codes (DTCs) related to the AC system.

Solution

1. Preparation

Gather tools and parts needed:
- Tools: Manifold gauge set, socket set, screwdrivers, safety glasses, gloves
- Parts: Refrigerant (as needed), AC compressor (if faulty), cabin air filter (if dirty)
Ensure the vehicle is parked on a level surface and the engine is off.

2. Check and Recharge Refrigerant

Step 1: Connect the manifold gauge set to the low and high-pressure service ports.
Step 2: Read the pressure levels; if the low side is below the recommended range, the system may be low on refrigerant.
Step 3: If needed, add refrigerant according to the manufacturer's specifications. Use R-134a for this model.
Step 4: Monitor the pressures during the refill to avoid overcharging, which can cause damage.

3. Inspect AC Components

Step 1: Visually inspect the AC compressor for any signs of wear or leaks.
Step 2: Test the AC clutch by checking for engagement when the AC is turned on; if it does not engage, further inspection of the wiring and relay may be necessary.
Step 3: If the compressor is faulty, disconnect the battery and remove it using a socket set. Replace it with a new unit according to manufacturer specifications.

4. Replace Cabin Air Filter

Step 1: Locate the cabin air filter compartment, usually behind the glove box.
Step 2: Remove the glove box to access the filter (release the retaining clips).
Step 3: Take out the old cabin air filter and install a new one, ensuring it is oriented correctly.