Affected vehicles: 2005-’08 A6

Condition: With the same temperature settings, different temperature air comes from the outlet vents on the driver side and passenger side. The outside outlet vents release warm air, and the inside outlet vents release cool air.

Technical Background: Debris remaining inside the engine block during production blocks the pump valve unit. As a result, one valve can stay permanently open, allowing warm coolant to flow into one of the heat exchangers. Other factors may be the electrical connector is not seated completely or the pin is pressed out; the outside temperature sensor G17 shows ­incorrect value; and/or the pump valve unit is faulty.

Service:

1. Turn both sides on Low. If the temperatures on the driver and passenger sides do not clearly drop to a reasonably equal temperature (one side is warmer than the other), a valve in the pump valve unit is blocked. Replace the pump valve unit.

2. Check the electrical connector on the pump valve unit in the plenum chamber (Fig. 1). Seat the plug correctly, or repair the pin with repair case VAS 1978A.

3. If the VIN is between 4F_5N065500 and 4F_6N026537, complete the procedure in TSB 2010148, Outside Temperature Display Too Low, Air Conditioning Undefined.

4. Turn both sides on Low. If the temperatures on the driver and passenger sides are hot and remain so, cycle the ignition key off, then on. If the condition is corrected merely from the key cycle, replace the pump valve unit with P/N 4F1 959 617B.

Tip: Do not replace the display and operating unit for the climate control system, as this will not resolve this condition.

Courtesy of Mitchell 1.