I know there are several threads on AC, and I've probably looked at them all by now.

Here's where I'm at:

Replaced accumulator, evac'd/recharged system, worked great for my 1hr drive back home.
Got home and noticed a teeni leak at the LP sensor, went it to get a wrench, by the time I got back out, the AC had stopped running.

From the forums and offline advice from Tech, I have replaced, one at a time, the high pressure sensor, blower motor resistor and compressor relay.

Some observations:
Compressor will come on and make nice cold air when jumpering the relay.
Engine cooling fan does not come on when AC button is depressed.
The low pressure switch is OK.
13v on both sides of relay coil (the control lines to the relay)
Tried multiple HP switches in case 1st used one was bad

I know it's a pain, but does anyone know how to bypass the high pressure switch?

Anything I've missed?

Thanks,
Chris

 

I wish I had the car here to look at it and read the codes. I wish you were closer to me.

 

Me too

I have not checked to see if there is too much pressure yet, but doubt it seeing that it worked so well for the ride home.

Tonight I noticed that when I forced the it on for a minute, seemed like the high side/orifice tube got hot. Can't really tell if it was hot from the temp of the engine or from use of the AC.

I'll make an appt with my local Volvo professional and report back.

Are there any inexpensive scan tools or programs that will do the Volvo specific codes?

Chris

 

There is one the S80 guys are using but not sure if it works on the S70.

 

Shop said there was a code in the system for the LP sensor and that was causing it not to come on. Would an existing code cause the system not to work at all? Does the code really need to be cleared to turn it on? They said the code probably ocurred because I removed the connector while the engine was running...makes sense. They ran it for a while and then said it shut off after a bit because of a bad AC clutch. They want $300 for the clutch + labor, they would not reshim it for me.

Since I have no way to clear AC codes, guess I should disconnect the battery to reset them in the future...will that do it?

Chris

 

That might do it. I have disconnected the LP switch and never had a problem with the stored code stopping it.
If you paid a check out fee they should have cleared the codes.

 

Yeah, theyporked me pretty good. $120 to clear the code, to turn the compressor back on to tell me something I would have been able to figure out if the the code wasn't keeping the compressor off in the first place

Quoted $428 for the clutch with labor.

They wouldn't even reset my service reminder light for free...gimme a break.

Tech, what's your take on the "bread-clip" shim method? Does your shop do reshimming or just install a new clutch. Seems like they only last around 80k before needing the shims.

Chris

 

Sorry I do not like the bread tie fix.

We reshim the compressor at our shop.

 

So assuming that the clutch is either bad or needs to be reshimmed, tonite I tried the two things. First I pushed on the outside of the clutch with a wooden stick, it did not re-engage. I then measured the power line going to the clutch. Power on that line cycles with the engaging and disengaging. If I jumper the relay the clutch will engage. It seems to me that something is telling the AC not to come on.

AC works great when you first start the car or on the highway. Once the car is warmed, or you get off the highway and hit traffic lights, the AC cycles and eventually stops cycling and does not come on at all.

Would you agree that the clutch is most likely not the problem? I'm going to end up bringing it back to the mechanics and making them look at it again at no charge.

Chris

 

When sitting still and A/C on does the cooling fan come on?

 

Yes, the cooling fan now always comes on when the AC button is depressed, whether or not the clutch is engaged.

 

Ok something is telling one of the switches to turn off.
Sounds like it is something due to temp. Where did you test for power?
Does the compressor have a temp shutoff switch on the back side?

 

I tested for power on the grey wire coming from the compressor. I stabbed the wire just above the inline connector. I don't know if there it has a temp sensor. How would I identify it?

 

Follow the wire from the white plug. See if it goes into a sensor in the back of the compressor before going to the clutch.

 

Ok, will do. I'll also look at the evap temp sensor. Can either of those be bypassed for testing?

 

I forget what year the car is. But if it is 2000 or older it will not have an evap temp sensor.

 

It's a 98. Ok. I just looked at a pic of a compressor with the sensor. I believe mine has the sensor, but I checked power before it goes into the sensor. It looks like it is a one wire sensor which just cuts power to the compressor and has no feedback to the rest of the system?

 

Bypass the sensor and see if it makes a difference.