2007 M35x AC

cheekymonkey

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Hi all,

I have an a/c that doesn't blow cool air. Here's what I know and have done:

1. Pressure is good and there is enough refrigerant in the system.
2. The compressor clutch doesn't engage
3. Ran the detailed diagnostic test (turn on engine > audio off > settings > rotate volume knob ) and saw some error "2-23" in the Error History (Detailed). Ironic, as it's not very detailed or helpful. Can't find any references to "2-23"
4. The Climate Control test did not return any error, but seemed to be stuck in a loop. Let it run for about 20 mins before I gave up. The magnetic clutch never engaged.
5. Checked the IPDM fuses and didn't see any that were burned
6. Seems the relays related to A/C in the IPDM are integrated so I'd have to replace the whole module if it failed. Sucks.
7. Looked at the low pressure switch, but not sure how to test it.
8. I've read conflicting info about the low pressure switch a) checking for continuity and b) bridging jumpers to engage. I took a multi meter and didn't see any continuity across any of the three pins of the switch. I also don't want to jump as there are reports that it may fry critical circuitry. Some say that the ECM is expecting a 0-5V signal on one of the pins and jumping wouldn't help anyways.

So that's where I'm at now. I'd like to know how to locate the problem. As I see it, we're down to three potential areas: switch, IPDM, or the compressor. Does anyone know how to troubleshoot any of those areas so I can go through the process of elimination? I bought a switch and I was going to replace it, but then realized I have to evacuate the system, so it would be a bummer if I did that and it wasn't related. The IPDM is anywhere from $50-$100 used, and of course the compressor is much more in terms of cost and labor.

Much thanks
 
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