Checking heat output and (actuation of temperature flaps) on vehicles fitted with a manually controlled air conditioner — VW

🧭 Before you start

Fits: VW Passat B8 (3G, 2014–)

📋 Procedure

1. Close bonnet, doors, windows and sunroof.
2. Open all dash panel vents.
3. Start the engine and make the following settings on the operating unit:
4. With the engine running, operate the air conditioner for several minutes at maximum cooling output.
5. Use a thermometer to measure the temperature of the air emerging from the left and right dash panel vents.

6. Compare the measured values to the measured value displayed for the evaporator temperature sensor G308vehicle diagnostic tester in "“Guided fault finding”" mode.
7. Set the highest possible temperature.
8. Use a thermometer to measure the temperature of the air emerging from the left and right dash panel vents. [Note: On vehicles with no V51, set the engine speed to roughly 2000 rpm and repeat the test if necessary. If the temperature of the air increases above 55 °C on repeating the test at increased engine speed, this is an indication that not enough coolant is flowing through the heating system heat exchanger. Cause: inadequate engine coolant pump delivery at idle or heat exchanger for heater not incorporated into the coolant circuit in the specified manner 19Cooling system, coolant; Coolant hose schematic diagram, vehicles with high-voltage system (coolant hose schematic diagram).The required heat output is not attained if insufficient heated coolant flows through the heating system heat exchanger.]
9. Set the lowest possible temperature.
10. Use a thermometer to measure the temperature of the air emerging from the left and right dash panel vents.
11. Compare the measured values to the measured value displayed for the evaporator temperature sensor G308vehicle diagnostic tester in "“Guided fault finding”" mode.

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