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A/C Performance Test

Perform this test if the cooling output seems reduced. A thermometer with a probe is necessary for the test.

NOTE -

Reduced cooling output on 1985 to 1987 Jettas may be caused by a malfunctioning expansion valve due to excess engine heat. A special valve insulator, part no. 191 820 692, is available from an authorized Volkswagen dealer to reduce expansion valve temperatures.

To test the A/C, open all instrument panel vents and place the thermometer into the left center vent. Run the engine until warm, then set the idle at 2000 rpm with the parking brake firmly set. Move the upper control lever to MAX A/C and the temperature control to cold. Close the windows and doors. After the A/C compressor has cycled off for the first time, record the temperature. It should be within the range given in Fig. 9-2. If it is not, make sure that the air flow is coming only from the center vents and that the recirculation door is closed. See 4.5 Heater and Controls for vacuum system troubleshooting. A temperature difference less than the specified value indicates a problem with the system. Inspect the system as described earlier.

Fig. 9-2. A/C system cooling range (B) based on ambient outside temperature (A) measured at left center vent with A/C set at MAX.

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