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Using Electrocooler with the Porsche CCU in Porsche 964 and 993

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HI All,

After a period of running, some users experience electric compressor switch off even if the snowflake button is still pressed.  This is due to additional logic in the Porsche CCU that used to turn the mechanical compressor off when the temperature fell below a certain threshold.   This is not desirable behaviour with the electric compressor as it is speed regulated by our ECU and is meant to remain running.

To fix this behaviour, the CCU can be 'fooled' by biasing the evaporator temperature sensor.  This is done by putting a 47k resistor in parallel / across the evaporator sensor.

1) Pull the sensor out of the air box.  It is located just to the left of the expansion block.


2) Trim back the insulation and solder the resistor across the 2 wires.    Tape and insulate.  Push the sensor back into the blower unit.


Resistors is a standard 1/2w 47k 'through hole' type.


Resistor available here:


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