BMW E38 air conditioning not cooling
Why is the E38 air conditioning not cooling?
The most common causes are a refrigerant leak, a fault in the compressor's magnetic clutch or the compressor, and a break in the fan control. The yellow leak-detection dye in the engine bay reveals the leak point, and the leaking joint or hose must be repaired.
Why does the A/C compressor not engage?
The A/C panel requests the compressor from the engine management. Engagement requires, among other things, the blower at power level 1 or higher, the engine below 99 °C and over 600 rpm. The pressure switch lets current through from 2.8 bar and cuts it off at 33 bar. If the supply voltage is 12 V but the compressor does not engage, the magnetic clutch is broken.
The A/C does not cool at idle, what is wrong?
The cooling fan may not be starting. Check that it gets operating voltage from the 50 A fuse in the engine bay, and measure the control wire. A corroded control wire is a typical cause. A seized compressor also shows as knocking and a melted belt.
Why does the A/C blow warm air?
If the hot water valve of the heater core is stuck open, hot coolant circulates through the core all the time. If you want cool air, also check that the recirculation arrow button is not on; the snowflake button switches the air conditioning on.