hi list,

I am trying to repair my A/C, and there seem to be a problem with the high pressure switch.
Mine is open, as well as the other switch of the HPS. My understanding is that is should be closed, and that if it is opened, then the other switch of the HPS sould be closed.
Am I right ? the switch is bad ?

And another thing, from a drawing at fcpeuro, it seems that there is a schraeder valve on the HPS. In this case I could change it after the refill of the A/C circuit. On other docs, the valve is not mentionned.
Does anybody have an answer ?

Thank yo for your help.

 

I am not aware of a HPS on a 94, LPS only. Evacuate the system and recharge with the specified amount listed on the yellow sticker on the passenger strut mount.

Simple test for your pressure switch. Start the car, turn on the A/C and put a jumper across the plug of the pressure switch. If the compressor fires up, replace the switch. If not its something else.

A very very common issue with A/C not working is the distance between the clutch and pulley. The rubber damper/spacers wear out causing the distance to increase between the clutch and pulley. The gap is to large and it cannot get a good enough magnetic field to latch on. The solution is to put spacers behind the rubber damper/spacers to push the clutch closer to the pulley.

 

hi boxpin, thank you for taking time to reply to my question.
There are indeed a HPS and a LPS (pressostat) on my 94 850.
The LPS is open, which is "normal" as the circuit is probalby empty do to a leakage.
To get the compressor running, I have to short both switches. The clutch is working.
So the only thing is I want to be sure that indeed the HPS is normally closed, and if it is opened, it means that I have to change it.

 

Can you post a picture of the HPS please?

 

Thank you for your interest in my problem.
Nobody seems to have a solution, so I ordered the part. I will ask the person servicing the a/c to change it. We will see.

This diagram shows a schraeder valver with the HPS :
Air conditioning 1994-. Fits: Volvo | VolvoPartsWebstore.com

This however does not mention it, but it is for a '95 build :
Volvo 850 AC service & repair manual

This is my valve, with the 4 pins connector :
Volvo A/C Trinary Switch Genuine Volvo 9132754 | FCP Euro

and this is the picture of my HPS :
see attachement

 

end of the story :
I received a new HPS, and it measured exactly as the HPS installed in the car.
The mechanic found no leak, just the system was missing gaz. Now the a/c seems to work fine.
So the HPS is normally open, only if there is enough pressure in the system.
I still don't know if there is a shraeder valve.