Does PCM Control A/C Compressor
Thread Starter
Heel & Toe
Joined: Oct 2006
Posts: 16
Likes: 0
Does PCM Control A/C Compressor
I have a Katech LS2 engine with a speartech harness. I thought that the PCM controlled the AC compressor CLuth and High pressure switch as in a C5, but Speartech is telling me that in the newer LS2 cars the PCM was not the one doing this, but rather the BCM was. THis makes no sense to me, since the PCM gets the WOT, RPM signals, and pressure sensor signals.
can anyone shed some light on this for me?
can anyone shed some light on this for me?
Safety Car
Joined: Jun 2004
Posts: 3,563
Likes: 2
From: Dallas Tx
The C6 doesn't have a PCM. It uses an ECM and BCM. I looked at both an 06 and 07 C6 service manuals. Both show the compressor being controlled by the ECM.
The ECM has inputs from the HVAC control module and A/C refrig pressure sensor, then has a circuit (pin63 dk green & white) that controls the A/C compressor clutch.
That circuit coming from the ECM pin 63 goes to the Underhood fuse block which has the A/C compressor relay, powertrain ign relay, and A/C comp fuse.
Coming out of the Underhood fuse block at B5 is a Dark Green wire going to the A/C compressor clutch, then a black wire from the clutch to ground (G102).
Now, that's the A/C Compressor Control circuit. The BCM affects so many systems and is on the LAN network, so it is also possible a BCM problem affects the A/C.
The ECM has inputs from the HVAC control module and A/C refrig pressure sensor, then has a circuit (pin63 dk green & white) that controls the A/C compressor clutch.
That circuit coming from the ECM pin 63 goes to the Underhood fuse block which has the A/C compressor relay, powertrain ign relay, and A/C comp fuse.
Coming out of the Underhood fuse block at B5 is a Dark Green wire going to the A/C compressor clutch, then a black wire from the clutch to ground (G102).
Now, that's the A/C Compressor Control circuit. The BCM affects so many systems and is on the LAN network, so it is also possible a BCM problem affects the A/C.
