VW Touran A/C Failure, Compressor Won't Engage

I dealt with similar symptoms on my 2011 VW Tiguan when the AC stopped working. The check engine light pointed to an undervoltage issue affecting the HVAC system. The root cause turned out to be a faulty AC relay and damaged wiring harness connection to the compressor clutch. The compressor itself was fine, but the electrical fault prevented it from engaging. A refrigerant leak test was performed but showed no issues with the system pressure. This was a serious electrical problem that required: Replacing the AC relay, Repairing the wiring harness, Testing the entire A/C system operation, Clearing fault codes The compressor not engaging is often misdiagnosed as a mechanical failure, when electrical issues are frequently the culprit. Based on your symptoms, I recommend having the relay and electrical connections checked first before assuming compressor replacement is needed. Make sure the shop does proper diagnostic testing of the HVAC system voltage and doesnt just jump to conclusions about refrigerant leaks or failed components. Getting the right diagnosis is crucial for this type of issue.

Thanks for sharing your experience. I had almost identical symptoms with my Touran last summer. The A/C compressor would not engage and the check engine light kept coming on. Just like in your case, what initially seemed like a major compressor failure turned out to be an electrical issue with the pressure switch. Would you mind sharing how much the repair ended up costing you? Also curious if youve had any issues since the fix was done? My repair was successful but Id like to compare notes since these electrical HVAC system problems can sometimes come back.

After getting the undervoltage issue fixed at the shop last month for 240€, my Tiguan AC system has been working flawlessly. The mechanic identified and repaired the faulty AC relay switch which was causing the compressor shut off problem. The pressure sensor readings are now stable and the electrical system is maintaining proper voltage to the compressor clutch. No more intermittent shutdowns or check engine lights. The belt tensioner was also inspected during the repair and showed no signs of wear. This type of electrical repair can seem expensive but its much more cost effective than replacing the entire compressor. A proper diagnosis of the relay and wiring is crucial since HVAC electrical problems often get misdiagnosed as refrigerant leaks or mechanical failures. Based on how the system is performing now, Im confident the root cause was properly addressed. The AC blows consistently cold and the compressor engages smoothly every time.

I finally decided to take my Touran to a trusted mechanic recommended by a. The total repair came to 280€, which included diagnosing and replacing the faulty pressure switch, checking the air conditioning system, and clearing the fault codes. Looking back, I was really worried it would be a major compressor replacement, so I feel relieved it was just an electrical issue. The mechanic showed me how the pressure sensor was sending incorrect signals to the AC relay, which explained why the compressor wasnt engaging. They also performed a complete system pressure test to confirm there were no refrigerant leaks. Its been about 3 months since the repair, and the air conditioning has been working perfectly. No more check engine lights or compressor engagement issues. The cold air flow is actually better than before, and the system engages immediately when I turn it on. For anyone facing similar symptoms, definitely get the electrical components checked before assuming the worst. Sometimes what seems like a major AC compressor failure can be fixed with a much simpler electrical repair.