Check ground connection for A/C pushbutton control module (N22) by turning ignition "ON" and pressing . Connect voltmeter ( + ) to terminal block, terminal 30/30U/61e/87L (X4/10) and test both connections of dual function A/C compressor pressure switch (S31/1) in series for ground. If there is no ground signal on either connection test the A/C compressor signal ( 23 25.0 ). If there is a ground signal to only one of the connections, test A/C system pressure. If the pressure is above 3 bar, replace dual function A/C compressor pressure switch (S31/1). If the pressure is below 2 bar, add 200 g refrigerant (R12 or R134a). Check for leaks and repaair if necessary (see connection diagram for signal test).

Conventional tools, test equipment

Description	Brand, model, etc.
Multimeter 1)	Fluke models 23, 83, 85, 87

1) Available through the MBUSA Standard Equipment Program.