2005ish xc90 AC pressures strange

Kongztt gt28rs MD · Post by **Kongztt gt28rs MD** » 20 May 2015, 11:32

Hey guys.

Working on a friend's 2005 xc90

Symptom :ac not cold except occasionally when fan was on low speed setting.

-compressor is engaging.
-Suction pipe is semi cold(not sweating .. Discharge is warm)
-fan is running

I hooked up my manifold gauges.. Strange I got suction (low side) pressure (~60-80psi)..

Discharge (high side) pressure I got about 100psi).

I know it should be much different.. Low should be about 35psi and high ~180psi.

At first.. I suspected a stuck open expansion valve.. But then I remembered this compressor has the control valve that I have read fails.

I couldn't find how to test it.. But I checked the Ohm and it was about 12.2 Ohm with it disconnected from harness.

I attempted to let some refrigerant out to bring the suction side down.. I got it down to about 50psi..but the high side also dropped to ~75psi.

The compressor clutch is engaged and compressor sounds smooth. Is this a typical failure of the compressor control valve that I can replace for about ~$100?

Or do you believe it's the compressor itself that is bad?

I'd like to save him some money if possible.. I'm hoping I can just recover the remaining refrigerant.. Replace the Compressor control valve.. Add oil and recharge.

Thanks for any help you can lend!

Post by **oragex** » 20 May 2015, 15:36

I don't know much about the a/c, but I remember someone having an issue with a temp sensor connected with the a/c. It was inside, under the dash somewhere near the gas pedal on the side of the center console.

Kongztt gt28rs MD · Post by **Kongztt gt28rs MD** » 21 May 2015, 05:29

I appreciate the reply.

But I don't think the temp sensor would have much to do with the pressure readings I'm seeing.

From what I gathered.. If compressor is running/engaged.. And the pressure is equal on both sides.. That usually would mean the compressor is bad.. However.. This isn't that way.. Which makes me feel it's the compressor control valve that is held into the compressor via snap ring.

I've never dealt with this type of compressor (VDP Variable displacement pump).. Volkswagen uses the similar design.

http://forums.tdiclub.com/showthread.php?t=283967

That is a link I am across. And remember reading something similar on a volvo forum before.

I hope others will chime in.. Because I keep seeing other posts on this site with some people that seem very knowledgeable about these compressors and systems. I hope they see and reply to this post.

Thanks!

Shawn

Post by **jimmy57** » 21 May 2015, 05:49

Only the V8 engine XC90 would have the VD compressor in 2005.
If it is not a V8 then that is not a possibility. Models w/o VD compressor could still have a faulty compressor and have those pressures due to poor pumping output of compressor.

Kongztt gt28rs MD · Post by **Kongztt gt28rs MD** » 21 May 2015, 06:16

Maybe I am using the wrong terminology? But this control valve

PN:31305844

This is the item I am talking about.. I did see this on his compressor..

I used my multimeter and got 12.2 ohm. With it disconnected (testing valve itself.. I don't know the proper range for this though)

Stupidly.. I didn't even pay attention if it's v8 or v6 etc.

I beleive this is what the VW forums were talking about.. As it has the same function.. Of allowing refrigerant to pass to low/high side.

I have not disassembled the compressor as he needs the vehicle.. Lives about 1.5hrs from me and I only opportunity to diagnose is while at work. I wanted to narrow it down.. Order the parts.. So that when they come in.. I can take his vehicle home and replace.. Clean.. Pull vacuum and recharge/oil with new drier

Or am I mistaken?

More answers the better!

Thank you!

Kongztt gt28rs MD · Post by **Kongztt gt28rs MD** » 26 May 2015, 07:37

Hey.. I had some miscommunication.

I find out.. It's a 2008 xc90 6cylider.

Kongztt gt28rs MD · Post by **Kongztt gt28rs MD** » 26 May 2015, 07:39

This is the VIN

he owner thought it was a v8 the whole time he has had it.

Post by **jimmy57** » 26 May 2015, 08:09

Yes, that model also has a variable displacement compressor. The solenoid controls crankcase pressure and crankcase pressure affects swash plate angle and thus piston stroke. The evaporator temp sensor is read by the climate control system and then a compressor work level message is sent via CAN to the ECM and the ECM is wired to the solenoid to control it with a PWM signal. The solenoids can bind.

Kongztt gt28rs MD · Post by **Kongztt gt28rs MD** » 26 May 2015, 10:21

Ah thank you for replying.

Do you happen to know a way I could test the refrigerant control VALVE (RCV) ?

I suspect this is the issue due to the odd pressures I'm finding.

Or possibly do you know the symptoms of a bad RCV? This a common failure? I know many just get instructed to replace the whole compressor.. But this is much cheaper to do it this way if this is the issue.

Kongztt gt28rs MD · Post by **Kongztt gt28rs MD** » 26 May 2015, 11:49

I just ran across this.

Post#1 and #12

He replaced the RCV on this 2007 xc90.

I attempted to join that forum but the captcha or whatever image was just ridiculously illegible

http://forums.swedespeed.com/showthread ... oting-help