Another Car, Another Climate Issue. AC This Time. Topic is solved

[V50M66]

That’s static pressure with the compressor not engaged, simply to verify my sensor is working properly. 400 kPa equates to ~58psi, which is what my gauge was showing, so it seems to be working. I can’t get the compressor to engage at all

[abscate]

But it still engages briefly when you first command it, then drops out?

[V50M66]

But it still engages briefly when you first command it, then drops out?

No, that was only the first time, when first filling the system. It refuses to engage at all now.

[abscate]

If you put 12v right onto the clutch wire does it pull in?

[V50M66]

If you put 12v right onto the clutch wire does it pull in?

Yeah. Also engages if I jump the relay pins in the fuse box. And engages during the relay test with the app posted above. It just doesn't want to work when it should under normal operation - it's not activating the relay

[wizechatmgr]

If you put 12v right onto the clutch wire does it pull in?

Yeah. Also engages if I jump the relay pins in the fuse box. And engages during the relay test with the app posted above. It just doesn't want to work when it should under normal operation - it's not activating the relay

If I had to guess it's going to be a sensor issue where it thinks the pressure is too high or low in the system somewhere then. Have you tried a different CCM unit for giggles?

Scratch that, you said MCC. Darn it. Still say I'd check the pressures reporting. That sounds a bit low at rest to me, but I haven't checked mine recently.

[V50M66]

If you put 12v right onto the clutch wire does it pull in?

Yeah. Also engages if I jump the relay pins in the fuse box. And engages during the relay test with the app posted above. It just doesn't want to work when it should under normal operation - it's not activating the relay

If I had to guess it's going to be a sensor issue where it thinks the pressure is too high or low in the system somewhere then. Have you tried a different CCM unit for giggles?

Scratch that, you said MCC. Darn it. Still say I'd check the pressures reporting. That sounds a bit low at rest to me, but I haven't checked mine recently.

Yep, tried a new MCC module with no changes unfortunately.

There's only 2 sensors in this system:

The high-pressure cutoff switch is a binary pressure switch that either allows or disallows current flow based on pressure. I've tried bypassing it (jumpering the pins) and replacing it, and all electrical measurements at both the sensor and the wiring are what they should be per VIDA, so that's not the problem.

The only other sensor is the low pressure sensor, which senses actual system pressure and reports it to the ECU. This one is reading within 10% of the crappy analog gauge attached to my AC charge hose, so I don't think this is the issue either, but I'm not sure what else could be the problem here.

[abscate]

So everything works up to the 4/46 ( that’s the ECU isn’t it) which isn’t commanding compressor on.

Fire up VOL FCR and check for MCC codes , there’s probably something stuck in the baffles

[xanthefin]

The Volvo own literature talks of 70 series code reading through its led on REC button and not anything of reader device for MCC.

Press REC button within 2 seconds after turning Ignition on > release and press twice the button > led will start flashing if any codes.
Removing codes is similar but pressing four times.

[abscate]

Yeah. Also engages if I jump the relay pins in the fuse box. And engages during the relay test with the app posted above. It just doesn't want to work when it should under normal operation - it's not activating the relay

If I had to guess it's going to be a sensor issue where it thinks the pressure is too high or low in the system somewhere then. Have you tried a different CCM unit for giggles?

Scratch that, you said MCC. Darn it. Still say I'd check the pressures reporting. That sounds a bit low at rest to me, but I haven't checked mine recently.

Yep, tried a new MCC module with no changes unfortunately.

There's only 2 sensors in this system:

The high-pressure cutoff switch is a binary pressure switch that either allows or disallows current flow based on pressure. I've tried bypassing it (jumpering the pins) and replacing it, and all electrical measurements at both the sensor and the wiring are what they should be per VIDA, so that's not the problem.

The only other sensor is the low pressure sensor, which senses actual system pressure and reports it to the ECU. This one is reading within 10% of the crappy analog gauge attached to my AC charge hose, so I don't think this is the issue either, but I'm not sure what else could be the problem here.

Other way around I think.

The low pressure switch is a binary 1/0

The high pressure switch or pressostat supplies a voltage proportional to high side pressure