A/C, Out

The coolant temperature is continually registered by the Electronic Display Unit (EDU) control module. To reduce the load at high temperatures (and so protect the engine from overheating), the A/C compressor is disconnected at a certain engine temperature.

If the engine temperature is lower than the temperature for A/C disconnection, the control module supplies battery positive voltage to pin 4 which is connected via pressure switch and anti-freeze thermostat to the Trionic/Motronic control module which, when their conditions for A/C connection have been met, ground the A/C relay.

4 cyl 6 cyl

A/C disconnected at ° C (° F) 119(246) 116(241)
connected at ° C (° F) 118(244) 115(239)