2005 XC 90 V8 A/C Problems

[wgc2005]

I know there have been a lot of posts written about the A/C cooling issues and shimming. However, I have not found any that specifically identify how to diagnose the problem. My XC90 is cooling, but not properly. I first started by checking the R-134a pressures. I used the A/C Pro brand with gauge. It wasn't showing low, however I did add some until it showed on the top end of the green area. Roughly 50 psi if I remember correctly. With the A/C on high I was able to get the air temp to about 65F coming out of the vents, but it still was not cold like normal. Next, I checked the cabin filter and it was dirty, however, I ran without the filter to test that theory and it made maybe 1-2F difference. I cannot audibly hear the compressor kick in and out when turning on and off the A/C, but if it is cooling I would think that the compressor would be working somewhat. Would I be correct in that thinking? Also, I am wondering what next steps to check to resolve this problem. If it is the compressor, how can I test to see? Thank you in advance.

[wgc2005]

UPDATE - In my previous post the ambient temp outside was roughly 95-100F. Today after changing out the passenger ball joint and both sway bar connectors, I figured I was already in this far let's try to play with the a/c some more. I removed the plastic wheel well so I could see the a/c compressor. It would engage and disengage when the a/c was turned on and off. Ambient temp today is about 80F. For some reason today the a/c will cool some. I can get the vents to read about 62F stationary and as low as 58F on the highway. Driver to passenger side is the same temp. I also switched the dual climate control to hot on one side and then the other to test some things I read in other posts. It responded properly to the control. I am now baffled. If the compressor is engaged, is it a shimming problem? What else can I check to narrow down issues? If it is a shimming issue, can someone share the method on the 2005 V8 style? Thank you.

[songzunhuang]

Have you tried the zip tie or bread clip trick? I had a similar problem on my other Volvo (a V70 T5). Over time the gap between the clutch and the pulley had gotten over spec so the compressor would periodically engage. If it is not engaged, you are not going to get a working A/C system. In short, the compressor turns the freon back to a liquid due to pressure. When the freon changes from a liquid to a gas, it absorbs heat and that's what makes an A/C cold. No compression, no liquid state for freon, no cooling.

Anyhow, it's something you could try pretty inexpensively. You can find several posts about this trick on the forum and on YouTube (yes look up Robert DIY).

[wgc2005]

I have not tried the bread clip trick yet. I haven't had time to get back into it. If I remember correctly, the compressor does not look the same as the examples I had seen for the bread clip. I may not remember correctly, but I don't remember seeing three bolts in which to put them under.

[Roger_850T]

I needed to shim my 850. In that case, it would work fine when I first started the car, and then it would stop working after everything got nice and hot under the hood. The theory was that as the electric coil in the AC clutch got hot, the resistance went up, the current went down, and the magnetic flux was no longer sufficient to engage the clutch through the wider gap, and there would be no AC.

If you can see the AC compressor spinning and you do not have sufficient cooling, it may suggest that your problem is elsewhere.

Roger

[wgc2005]

Roger, I tend to agree with the problem potentially being elsewhere. Last week it was fairly mild temperatures here (~75-85F) and it was at least bearable to drive the vehicle, but it still was not as cold as I had hoped. I cannot get my head around what I am seeing and why it is happening the way it is. There does not seem to be a rhyme or reason except on hot days it tends not to work, however on some cool days it doesn't work either, but those days are fewer. My thought process is this: R-134a levels (good), compressor engaged and spinning (good), cabin filter replaced and compartment vacuumed out (good). I know there are other components to an a/c system, but if the levels are good and the compressor is running, I cannot figure out why on hot days the outside air can be at times cooler than the air being blown out of the vents. My only thought is that the compressor works intermittently. I am not sure.

[jimmy57]

Bread clip trick should not be applicable as this compressor does not cycle so clutch wear is nil. V8 was first Volvo with variable displacement compressor. The compressor has a variable stroke that is regulated by a solenoid that controls crankcase pressure. The evaporator temp probe is read by Climate control module (CCM) and it sends a signal via network to ECM and ECM is the direct connection to the solenoid. Solenoids can stick and the temp probe over above accel pedal tuck in case can give wrong temps and cause compressor to be turned down.
The only sure way is to look at evap probe with VIDA or other scan tool with that capability and then check solenoid duty cycle VS a/c pressures if temp probe is accurate.

[abscate]

The cheap gauges are notoriously inaccurate, and it's also really easy to improperly charge AC based solely on pressure..

[Roger_850T]

Bread clip trick should not be applicable as this compressor does not cycle so clutch wear is nil. V8 was first Volvo with variable displacement compressor. The compressor has a variable stroke that is regulated by a solenoid that controls crankcase pressure. The evaporator temp probe is read by Climate control module (CCM) and it sends a signal via network to ECM and ECM is the direct connection to the solenoid. Solenoids can stick and the temp probe over above accel pedal tuck in case can give wrong temps and cause compressor to be turned down.
The only sure way is to look at evap probe with VIDA or other scan tool with that capability and then check solenoid duty cycle VS a/c pressures if temp probe is accurate.

Jimmy, that's very helpful, I did not know that! Do you have any information regarding what would be expected as normal for the solenoid duty cycle? I think I want to go and check mine to get a baseline against future issues...

Roger

[jimmy57]

Hot car, full fan within the fist few minutes will be 75% or even higher. application of solenoid drops crankcase pressure as it is a bleed. Lower crankcase pressure yields piston travel further to bottom of cylinder bore.