Checking Compressor Cutout and Remedial Measures
TESTING COMPRESSOR CUTOUT AND REMEDIESA. Testing with electromagnetic clutch of refrigerant compressor not connected
Attention!
A prerequisite for test is perfect functioning of refrigerant compressor activation.
For this purpose:
^ Switch on ignition, push mode selection button "central vents" and "max dehumidification" for air conditioning system.
^ Connect voltmeter to blue/white line (input) of pushbutton refrigerant compressor (22) and up to model year 84 to vehicle ground, starting model year 85 to positive. Nominal value: battery voltage. If there is no voltage, test air conditioning system according to wiring diagram.
^ Connect voltmeter to blue/red line (output) of pushbutton switch refrigerant compressor (22) and up to model year 84 to vehicle ground, starting model year 85 to positive. Nominal value: battery voltage.
If there is no voltage, test high pressure of air conditioning system. Renew pushbutton switch (22) at a pressure of >3 bar.
Refill air conditioning system at a pressure of <2 bar and eliminate leak.
B. Testing cutout of electromagnetic clutch of refrigerant compressor via control unit compressor cutout (141)
1 Run engine at idle speed.
2 Engage temperature wheel to "MIN", set blower to stage 4 and adjust mode selection buttons "central vents" and "max dehumidification".
3 Spray with a water jet in-between V-belt and pulley of electromagnetic clutch of refrigerant compressor until the refrigerant compressor is switched off, while applying intermittent acceleration. If the refrigerant compressor is not switched off by control unit (141), renew control unit.
Attention! Following cutout of refrigerant compressor, the compressor may be started again via control unit (141) after stopping and renewed starting of engine.
4 On model 201 with gasoline engine, check whether the refrigerant compressor is switched off by temperature switch 110 °C (23). For this purpose, start engine again, pull 1-pin connector from temperature switch 110 °C (23) and connect to ground.
The refrigerant compressor must be switched off immediately. If required, eliminate line interruption or renew control unit (141).
5 On model 201 with diesel engine and automatic transmission, check whether refrigerant compressor is switched off by micro switch 134/I as follows:
Run engine at die. Watch electromagnetic clutch of refrigerant compressor and apply full throttle for a short moment. The electromagnetic clutch must remain switched off up to 2150 rpm and then switch on again. If the electromagnetic clutch is not switched off, renew microswitch 134/I or control unit 141.