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

GMC Sierra T1XX (2019-Present)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

4 min read

645 words

Problem Statement

Learn how to diagnose and fix AC not blowing cold air in GMC Sierra T1XX (2019-Present). Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

Affected Component

HVAC

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Always wear safety goggles and gloves when handling refrigerants.
•Ensure the engine is off and the vehicle is cool before working on the AC system.
•Disconnect the battery before replacing electrical components.

Symptoms

•AC system blows warm air
•Unusual noises when the AC is running
•Inconsistent airflow from vents
•AC compressor not engaging
•Frost build-up on AC components

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to check for any AC-related trouble codes.
2
Inspect the AC refrigerant levels using a manifold gauge set to determine if the system is undercharged or overcharged.
3
Check the AC compressor operation by observing if the clutch engages when the AC is turned on.
4
Inspect the AC fuses and relays in the fuse box for any blown fuses or faulty relays.
5
Examine the cabin air filter for dirt and blockages that may restrict airflow.
6
Check for any visible leaks in the AC system components such as hoses, the condenser, and the evaporator.

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

•OBD-II scanner
•Manifold gauge set
•Refrigerant can with hose
•Standard socket set
•Screwdriver set

Parts Required

•Refrigerant (R-134a or R-1234yf as applicable)
•Cabin air filter
•AC compressor (if defective)
•Fuses/relays (if faulty)

Related Faults

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to check for any AC-related trouble codes.
2
Inspect the AC refrigerant levels using a manifold gauge set to determine if the system is undercharged or overcharged.
3
Check the AC compressor operation by observing if the clutch engages when the AC is turned on.
4
Inspect the AC fuses and relays in the fuse box for any blown fuses or faulty relays.
5
Examine the cabin air filter for dirt and blockages that may restrict airflow.
6
Check for any visible leaks in the AC system components such as hoses, the condenser, and the evaporator.

Solution

1. Preparation

Gather tools and materials: OBD-II scanner, manifold gauge set, replacement refrigerant, cabin air filter.
Ensure the vehicle is parked on a level surface and the engine is off.
Disconnect the negative battery cable to ensure safety.

2. Recharge AC System

Connect Manifold Gauges:
- Attach the low-pressure side gauge to the service port on the AC system.
- Attach the high-pressure side gauge to the high-pressure service port.
Check Refrigerant Levels:
- Start the engine and turn on the AC to the maximum setting.
- Read the gauges to determine if the refrigerant levels are low.
Add Refrigerant:
- If levels are low, connect the refrigerant can to the low-pressure side and open the valve to allow refrigerant to flow into the system.
- Monitor the gauge and stop adding once it reaches the manufacturer’s recommended pressure.

3. Replace Cabin Air Filter

Locate the Cabin Air Filter:
- Find the cabin air filter compartment, usually located behind the glove box or under the dashboard.
Remove Old Cabin Air Filter:
- Open the compartment and remove the old filter by pulling it out carefully.
Install New Cabin Air Filter:
- Insert the new filter, ensuring it is oriented correctly as per the airflow direction indicated on the filter.

4. Inspect and Replace AC Components (if needed)

AC Compressor Check:
- If the compressor is not engaging, check the electrical connections and replace the AC compressor if faulty.
Repair Refrigerant Leaks:
- Use UV dye to identify leaks in the AC system and replace any damaged hoses or components.
Replace Fuses/Relays:
- If any fuses or relays are found to be faulty, replace them with the correct rating.