E38 5.3 swap into Porsche 996 how to command ac compressor

[Amille28]

I can't seem to figure out how the E38 can be used to control the a/c relay.
The Porsche computer is fed inputs from the climate control computer (a PWM signal when on, no voltage when off) (2001 996 non CANBUS)
The Porsche computer also has a 5v pressure switch.

Is it possible to hook up the porsche ac demand and pressure switch to the E38 and control a ground to the A/C relay?
My problem is my fans are controlled by the E38 not the Porsche computer. Id like to have the GM side control the a/c relay as well.
What inputs are needed to make the E38 control supply a ground to the Porsche A/C relay?

[Amille28]

I'm wondering if i need something like RPMExtreme GM E38 A/C Request module?

[castorjames]

Yes sir thats what you need as the AC on the E38 is requested on canbus data, i havent used that module from RPMExtreme, but have used Jeep-GM canbus comunication translator from them with great succes

[Amille28]

thanks. Do you know if in addition to the CANBUS a/c request signal if i would need to hook up a pressure sensor to the E38

Here is my understanding of what the E38 does.

1. waits for a/c demand (snowflake a/c button to be turned on) on the CANBUS
2. monitors pressure on the hi side and controls fans when a/c is on this in cludes a ground wire, 5v reference and differential pressure signal wire
3. puts a ground to the a/c relay to activate compressor voltage and takes it away when either the a/c demand goes to OFF or the RPM cutoff is reached.

Do I have it right?

[rpmextreme]

thanks. Do you know if in addition to the CANBUS a/c request signal if i would need to hook up a pressure sensor to the E38

Here is my understanding of what the E38 does.

1. waits for a/c demand (snowflake a/c button to be turned on) on the CANBUS
2. monitors pressure on the hi side and controls fans when a/c is on this in cludes a ground wire, 5v reference and differential pressure signal wire
3. puts a ground to the a/c relay to activate compressor voltage and takes it away when either the a/c demand goes to OFF or the RPM cutoff is reached.

Do I have it right?

Yes you will need the GM AC pressure transducer wired up and working so the GM ECU can view the pressure properly. The AC request module will send the correct AC request signal to the ECU when signaled.