Tech Tips (by ALLDATA): VW Jetta A/C blows warm air
Vehicle: 2008 Volkswagen Jetta Sedan (1K2), L5-2.5L (CBTA), Automatic Transmission/Transaxle
Problem: The vehicle owner brought the car to the shop because the air conditioner (A/C) was blowing warm air.
Case Details: The technician did a great job at performing some basic tests. The scan tool showed no diagnostic trouble codes (DTCs). He also verified that there was sufficient refrigerant in the system. He noted that although the low and high-side static pressures were normal, the A/C compressor clutch would not engage. All related fuses had B+ voltage to them and they were not open or missing. A call to ALLDATA Tech-Assist provided some further diagnostic testing.
The Tech-Assist consultant advised monitoring the A/C Control Module compressor request and switch status. He also suggested verifying that there was B+ voltage at the compressor GRN/BLK wire (pin 2) and a ground at the BRN/BLK wire (pin 1).
The Tech verified that there was B+ voltage at the compressor GRN/BLK wire (pin 2), but there was no ground at the BRN/BLK wire (pin 1). He traced the circuit and found the BRN/BLK wire was open near ground G655, located below the left headlight assembly.
Confirmed Repair: After the open circuit was repaired, the A/C compressor clutch engaged, all system operating pressures were normal, and the A/C blew cold air. Fixed!