why does my Volkswagen Golf MK7.5 (2020-Present) AC not blow cold air anymore

Volkswagen Golf MK7.5 (2020-Present)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

4 min read

611 words

Problem Statement

Learn how to diagnose and fix AC issues in Volkswagen Golf MK7.5. 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

•Disconnect the battery before working on electrical systems.
•Wear safety goggles when handling refrigerants and working on the AC system.
•Ensure the engine is cool before starting any repairs.

Symptoms

•AC system blows warm air instead of cold
•AC compressor does not engage
•Unusual noises coming from the AC system
•Decreased airflow from the vents
•AC system cycles on and off frequently

Diagnostic Steps

1
Inspect the AC system's refrigerant level using a manifold gauge set.
2
Check for visible leaks in the AC lines, compressor, and evaporator.
3
Test the AC compressor’s electrical connections for voltage and ground.
4
Use a scan tool to check for any fault codes related to the AC system.
5
Inspect and test the AC relay for proper operation.
6
Verify the condition of the cabin air filter for blockages.

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
•Multimeter
•Basic hand tools
•Refrigerant canister
•Safety goggles

Parts Required

•Refrigerant (R-134a or specified type)
•AC compressor (if faulty)
•O-rings and seals (if leaks are found)
•Cabin air filter (if needed)

Related Faults

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Diagnostic Steps

1
Inspect the AC system's refrigerant level using a manifold gauge set.
2
Check for visible leaks in the AC lines, compressor, and evaporator.
3
Test the AC compressor’s electrical connections for voltage and ground.
4
Use a scan tool to check for any fault codes related to the AC system.
5
Inspect and test the AC relay for proper operation.
6
Verify the condition of the cabin air filter for blockages.

Solution

1. Preparation

Gather tools: manifold gauge set, multimeter, basic hand tools, and safety goggles.
Park the vehicle on a level surface and ensure the engine is off.
Disconnect the battery for safety.

2. Check and Recharge Refrigerant

Attach the low-pressure side of the manifold gauge to the service port.
Start the engine and set the AC to max cooling with the fan on high.
Read the gauge; if the pressure is low, proceed to recharge.
Connect a refrigerant canister to the low-pressure side and slowly add refrigerant until the correct level is reached (approximately 30-40 psi at 75°F ambient).
Remove the gauge set and reconnect the service port cap securely.

3. Inspect and Replace AC Compressor (if necessary)

If the compressor does not engage, locate the AC compressor and check the electrical connector for damage.
Use a multimeter to test for voltage at the compressor while the AC is on.
If no voltage is present, inspect the AC fuse and relay, replacing if necessary.
If the compressor is faulty, remove the serpentine belt, disconnect the AC lines, and unbolt the compressor from its mounting bracket.
Replace with a new compressor, ensuring to add the correct amount of oil (usually specified in the compressor manual).

4. Inspect and Repair Leaks

If refrigerant was low, conduct a leak test using UV dye or a nitrogen pressure test.
Locate leaks and repair components as needed (e.g., replacing O-rings, hoses, or the condenser).
After repairs, evacuate the system using a vacuum pump for at least 30 minutes to remove moisture.

5. Reassemble and Test

Reconnect all components, ensuring all fittings are tight.
Reconnect the battery and start the engine.
Test the AC system to confirm cold air is being produced.