why does my Volkswagen Golf MK7.5 (2020-Present) AC compressor run continuously

Volkswagen Golf MK7.5 (2020-Present)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

3 min read

507 words

Problem Statement

Learn how to diagnose and fix the issue of a continuously running AC compressor in your Volkswagen Golf MK7.5. Step-by-step guide included.

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 AC system to depressurize before servicing to avoid refrigerant release.

Symptoms

•AC compressor operates without cycling off
•Reduced cooling efficiency
•Increased engine load and potential overheating
•Unusual noises from the compressor
•Possible refrigerant leaks
•Intermittent AC performance

Diagnostic Steps

1
Inspect the AC system for refrigerant levels using a manifold gauge set.
2
Scan the vehicle's onboard diagnostics (OBD-II) for any fault codes related to the AC system.
3
Check the operation of the AC clutch and compressor engagement.
4
Examine the cabin temperature sensor and related wiring for faults.
5
Test the functionality of the AC control module.
6
Inspect the AC pressure switch for proper operation.

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
•OBD-II scanner
•Socket set
•Screwdrivers

Parts Required

•AC pressure switch
•Cabin temperature sensor
•Refrigerant

Related Faults

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Diagnostic Steps

1
Inspect the AC system for refrigerant levels using a manifold gauge set.
2
Scan the vehicle's onboard diagnostics (OBD-II) for any fault codes related to the AC system.
3
Check the operation of the AC clutch and compressor engagement.
4
Examine the cabin temperature sensor and related wiring for faults.
5
Test the functionality of the AC control module.
6
Inspect the AC pressure switch for proper operation.

Solution

1. Preparation

Gather tools and parts needed for the repair.
Disconnect the battery to avoid electrical shocks.

2. Recharge Refrigerant

Connect the manifold gauge set to the low and high-pressure service ports.
Check the refrigerant level; if low, proceed to recharge:
- Open the low-side valve and add refrigerant until the correct pressure is reached (typically between 30-40 psi).
- Monitor the high-side pressure (should be between 150-250 psi depending on ambient temperature).

3. Inspect and Replace AC Pressure Switch

Locate the AC pressure switch on the AC line.
Unplug the electrical connector from the switch.
Remove the switch using an appropriate socket.
Install the new AC pressure switch, ensuring it seals properly to avoid leaks.
Reconnect the electrical connector.

4. Check and Replace Cabin Temperature Sensor

Remove the dashboard panel to access the cabin temperature sensor.
Disconnect the electrical connector from the sensor.
Remove the sensor from its mounting location.
Install the new cabin temperature sensor and reconnect the connector.
Reassemble the dashboard panel.

5. Reconnect Battery and Test

Reconnect the vehicle’s battery.
Start the engine and turn on the AC to check for proper operation.
Monitor the compressor cycling to ensure it engages and disengages as designed.