AC turns on 1 sec then off. Full charge [Resolved, bad high pressure switch]

[abscate]

Your high pressure should be in the range of 150-200 psi.

That OBD data is suspect, it’s a data man table some wrote not specific for you car. If you don’t have a reader with Volvo specific software, you need to measure voltages on the back pins of the high pressure sensor.

I believe 1998 is the same as 1999 which is here

[Brickbox8398]

Your high pressure should be in the range of 150-200 psi.

That OBD data is suspect, it’s a data man table some wrote not specific for you car. If you don’t have a reader with Volvo specific software, you need to measure voltages on the back pins of the high pressure sensor.

I believe 1998 is the same as 1999 which is here

This is very helpful! Based on this info ignore the data in my last post. I didn’t know what I was doing. This time around I checked between 1-2 for signal and got 4.76v. Reference 1-3 is 4.98v. This is with the car on, ac on, compressor not engaged due to whatever issue I’m having. I then checked voltage with the relay jumped. STILL got the same voltages. You think my high pressure sensor is bad based on that? Based on the table in your post it looks like my sensor is maxed out reading high pressure. My obd850 app gave me a very similar kpa value too. I feel like I am getting somewhere finally. Might jump on ordering a sensor right now.

[abscate]

Those sensors are mega expensive, I should have a good used one I can send you

[Brickbox8398]

Those sensors are mega expensive, I should have a good used one I can send you

Thanks for the offer but I bought one on fleabay last night. It was only $50

[wizechatmgr]

Depending on the AC manifold set you have, I believe there is a schrader under that sensor - you may be able to hook the high side hose directly to it and see what you're getting while jumpering the compressor to get it to run.

[abscate]

I seem to recall the fitting under there is not a standard ac quick connect.

Label this as 80% true

Welcome home , wcm!

[Brickbox8398]

I am thrilled to announce that this will not be a dead end thread! It turns out my high pressure sensor was bad. Took 1 minute to replace. From my research this is an uncommon failure, but I was able to troubleshoot it via multimeter as my last few posts stated.