2002 V70 X/C AC -- Probably High Temp Switch

rlrhett · Post by **rlrhett** » 04 May 2014, 12:49

My car is exhibiting all the symptoms that I believe are common to a faulty high temperature switch. The A/C will work fine initially. I can see the clutch engaging. After a while, the clutch disengages. Pushing with a broom handle doesn't do anything (so I don't believe it is a gap issue). This happens sooner on hotter days, and rarely when the temp is only high 70's or low 80's. It seems to be irrelevant if the car is accelerating, and can even happen while the car is sitting in park. Eventually I can reset the A/C and it will blow cold for a short while before it stops. When it works, it woks as expected with good cooling.

I have seen several posts about a faulty high temp switch. The problem is that my compressor's wiring doesn't seem to match what others demonstrate. For example, I don't have two wires leading to the clutch, only one. Likewise there is no obvious sensor or switch anywhere along the two A/C pipes. All I have is this single plug with a single wire leading from the wiring harness (and disappearing below the engine), and a single wire leading to the clutch.

Can anyone tell me how to short/replace the high temperature switch on this configuration?

Thanks.

Post by **jimmy57** » 04 May 2014, 13:35

That doesn't look to have the high temp switch. On ones with the switch there are two connectors next to each other, the wire in has connector and that wire goes to switch and then the wire back from switch has connector docked there connected to wire to clutch.
Are you giving it a smart tap with the broom handle?

rlrhett · Post by **rlrhett** » 11 May 2014, 15:54

Thank you for the suggestions, but I really don't think it is the gap issue. I can push with the broom handle all I want to no effect (I can't really "tap" as that implies room to swing the handle. Obviously the gap between the compressor and the side fender wall is barely enough to slide a broom handle in.)

The new thing its doing is that it will cycle on and off, just as others have remarked when the pressure is low. However, the pressure is clearly not low. I am just using a pressure gage from the parts store, but it shows about 40-50 psi on a hot (85-95deg) day on the low side with the compressor engaged. The static pressure when the compressor is not engaged is about 80psi, for whatever that may be worth. By "cycle on and off" I mean it will engage for a second or less and immediately cut out. As I said, no amount of pushing on the plate can force it to re-engage. However it will re engage on its own every couple of minutes and immediately disengage.

There must, at least, have a low pressure switch. Don't all systems? Perhaps that is sending a low pressure signal that is faulty.

Any suggestions on how to troubleshoot this further? I can find no evidence of any switches, but perhaps I don't know where to look.

Post by **jimmy57** » 11 May 2014, 15:57

P2s use a thermostat sensor in evaporator to cycle compressor. The high pressure sensor is for fan decisions and if too high compressor will be shut off. Also shuts off comp if system is empty.
You could have an evaporator temp probe issue. Most year models are off at 4-5 C and on at 6-8 C degrees.

Post by **abscate** » 11 May 2014, 16:37

To really put the clutch issue to bed, you should measure it with a feeler gauge to see if it is within specs. I don't know the spec for the P2 cars, but someone with VIDA can help here, Im sure.

rlrhett · Post by **rlrhett** » 11 May 2014, 18:14

I measured the gap to be just about .4mm. Is that within spec?

Post by **abscate** » 11 May 2014, 18:26

1999 spec is 0.3-0.5mm and yours is probably the same.