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Discussion Starter #1
I have a 2007 XC90 with a V8.

The Air Conditioning has been working intermittently lately. My wife drives it and says that it'll work for a while, then stops. I have read many threads that state the solenoid in the compressor, or the compressor could be bad.

I did rent a manifold gauge from Autozone and took some readings today.

At first startup in the driveway, the A/C blew super cold and the pressure was at 40psi on the low and about 160 on the high side. The needles didn't move much. The high side fluctuated a little bit, but only about 5-10 psi. The compressor clutch stayed on all the time.

I took it for a drive and it worked great for 10 minutes. Stopped for gas and drove back home and it didn't work. I put the gauges on when I got home and the low side was at 50psi and the high was about 400psi. What? I didn't think it would ever get that high. The car was blowing ambient air, not cold. The radiator fan was spinning at a super fast speed also.

I opened up the high side valve in the manifold gauge for a split second and it dropped down to 300psi. Then fluctuated a bit and stabilized. I did it again and now it's back at 40psi on the low side and 200-220psi on the high side and blowing cool air again. When I did this , the radiator fan slowed down to what I would consider a normal speed. If I got the RPMs up to 1500-2000, it started blowing cold again.

What would cause the high side to go to 400psi? Is this a solenoid problem? Compressor problem? Something clogging the system somewhere?

I'd like to fix this myself and save money if possible, but could take it in if needed.

Thanks.
 

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Discussion Starter #2 (Edited)
I took it for another 10-15 mile drive and it worked the whole time. I shut the vehicle off half way through and the air kept working OK. It didn't seem as super cold as it did the first start of the day, but it was pretty cold.

Edit.... I have a grill temp thermometer that I put in the center vent when the A/C was on high and it read about 50F. (after correcting the calibration based on ambient temperature)

I got back home and the pressures are 38-40 on the low and 190-210 on the high side. Ambient temp has been 80-85 this morning.

Any suggestions?
 

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I took it for another 10-15 mile drive and it worked the whole time. I shut the vehicle off half way through and the air kept working OK. It didn't seem as super cold as it did the first start of the day, but it was pretty cold.

Edit.... I have a grill temp thermometer that I put in the center vent when the A/C was on high and it read about 50F. (after correcting the calibration based on ambient temperature)

I got back home and the pressures are 38-40 on the low and 190-210 on the high side. Ambient temp has been 80-85 this morning.

Any suggestions?
Sounds like your variable displacement compressor control valve is going bad, dirty and sticking do a search here I've posted a few resolutions to this none are step by step DIY but it's really simple job- 1. evacuate the system 2. R&R valve ( 10 minutes) 3. Refill system. I'd also put a new dryer while you're at it- Also counterintuitively sine the compressor varies output, you can't really tell what the high or low is reading on these engine without the VIDA being hooked up to the CCM to monitor output voltage and duty cycle % at target temps

I'm a BMW and Audi guy, my xc90 V8 is just for hauling football gear, photo equipment and now for towing an M3 track car and other such nonsense- Not sure what your budget is, but from experience buying an e39 M5 for anything less than 20k is going to cost you more in repairs than buying a good example to begin with. If you're looking for an E39 M5 this is one of the nicest lowest mile examples I've seen I'm still considering it it's in Denver http://denver.craigslist.org/cto/5609433730.html
 

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Discussion Starter #4
Sounds like your variable displacement compressor control valve is going bad, dirty and sticking do a search here I've posted a few resolutions to this none are step by step DIY but it's really simple job- 1. evacuate the system 2. R&R valve ( 10 minutes) 3. Refill system. I'd also put a new dryer while you're at it- Also counterintuitively sine the compressor varies output, you can't really tell what the high or low is reading on these engine without the VIDA being hooked up to the CCM to monitor output voltage and duty cycle % at target temps

I'm a BMW and Audi guy, my xc90 V8 is just for hauling football gear, photo equipment and now for towing an M3 track car and other such nonsense- Not sure what your budget is, but from experience buying an e39 M5 for anything less than 20k is going to cost you more in repairs than buying a good example to begin with. If you're looking for an E39 M5 this is one of the nicest lowest mile examples I've seen I'm still considering it it's in Denver http://denver.craigslist.org/cto/5609433730.html
Thanks for the info on the Volvo and BMW.

I just replaced the transmission fluid on the Volvo today. Now I need to get it into the shop for them to reset the ECU stuff related to that. Maybe they can check the A/C on the Vida/Dice thingy while they're at it. I just went for a drive, turned the air on high and checked the temp with my grill thermometer (not sure how accurate it is) and it's reading about 32F lower than ambient temperature (95F today). I'll have to get that A/C compressor solenoid/valve replaced.

I think I'm leaning towards 540i as I 'think' it may have a little less cost for maint/repairs. I have found some higher mileage 540i examples that have had the timing chain guides, valley gasket, clutch, thermostat, etc replace in the last 10-20k miles. They were $5000 to $8000. More in my price range.

That M5 sure does look nice though. And low miles. But, I'm also going to be using whatever I get as a daily driver. Not sure the M5 will be the right choice for that.
 

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Thanks for the info on the Volvo and BMW.

I just replaced the transmission fluid on the Volvo today. Now I need to get it into the shop for them to reset the ECU stuff related to that. Maybe they can check the A/C on the Vida/Dice thingy while they're at it. I just went for a drive, turned the air on high and checked the temp with my grill thermometer (not sure how accurate it is) and it's reading about 32F lower than ambient temperature (95F today). I'll have to get that A/C compressor solenoid/valve replaced.

I think I'm leaning towards 540i as I 'think' it may have a little less cost for maint/repairs. I have found some higher mileage 540i examples that have had the timing chain guides, valley gasket, clutch, thermostat, etc replace in the last 10-20k miles. They were $5000 to $8000. More in my price range.

That M5 sure does look nice though. And low miles. But, I'm also going to be using whatever I get as a daily driver. Not sure the M5 will be the right choice for that.
I'm about 90% sure it's the valve, they do work intermittently as the car heats up - mine did until it failed- here is the part # Part # 31305844 it literally takes about 10 or 15 minutes to replace the valve the evac and refill of the gas takes more time. Dealership will likely tell you to replace the whole compressor for about 1800 out the door - an indy mechanic will do it for far less. FWIW Not sure why you'd need to reset anything after a tranny fluid change, volvo procedures are sometimes pretty whacky IMO. I've done it before and never reset the fluid adaption counter and have never had an issue, the transmission adaption doesn't change in fact I removed and added almost 4 liters of new fluid when I added a transmission cooler last week and it still shifts perfectly. I understand that the TCM adapts the transmission based upon fluid temp, pressure etc and conceivably if the adaptation in the module is shifting based upon fluid at the end of its life 'shocking" it with new fluid which has better temperature properties and generated different internal pressures may cause issues
but if the car has had previous fluid changes I don't personally see the need.

Definitely a 540i M sport on the e39 front if that's your budget I'd look for an 03 540i M sport- that was the only year with the actual e39 M suspension parts previous "sports" were just manual tranny's and sport interior and external plastic the 03 is the peak of the e39's options and had the latest electronics and upgradability. Nice examples with paint history as you say can be had in the 6-9 k range. Daily driving an M5 is very doable but racking up the miles along with the statistical probability of an accident isn't worth it IMO- Here a nice example of what to look for albeit a bit out of your price range - https://www.cargurus.com/Cars/l-Used-2003-BMW-5-Series-540i-t37637#listing=145909727
 

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Discussion Starter #6
A question about replacing the valve in the compressor.
If I go to a shop and have them evacuate my system, then replace the parts myself, then go back to the shop and have them fill it back up again? Or do I do that myself with some oil and R-134a?
If a shop...how much should I expect to pay for them to do their work?
 

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A question about replacing the valve in the compressor.
If I go to a shop and have them evacuate my system, then replace the parts myself, then go back to the shop and have them fill it back up again? Or do I do that myself with some oil and R-134a?
If a shop...how much should I expect to pay for them to do their work?
I took it to the valvoline quick lube down the street from me, explained I needed it evacuated and would be back for the fill. They evacuated the system, I turned off the AC drove home replaced the valve and new dryer then drove back and they refilled it. I have a 7 passenger with rear air which takes a bit more refrigerant than the 5 passenger so make sure they look at the the sticker under the hood and put in the correct amount. I paid 79.00 at jiffylube for the vac and refill. You'll need a pair of snap ring pliers for the ring holding the valve in place there are several o rings which seal the valve a new valve should have them there is a pigtail plug which is easy to remove as well - take the skid plate off the the car and the compressor is the bottom accessory you can see the valve on the bottom of the com with our removing anything else here is what the valve looks like :

I found my steps for this in an old post here ya go-
1. remove metal skid plate
2. push lower radiator hose out of the way and use a flashlight or thin shop lamp to illuminate the area and hold the hose out of the way
2 use a long handled pair of snap ring pliers and remove the snap ring from the valve
3. unplug the wiring harness and remove from the harness plate
4. attach long nose vice grips to the valve or otherwise wiggle and pull it out rotating and pulling with even pressure ( there may be some remaining pressure in the system which escapes/.
5. put new o- rings on the new valve and the large o ring in the compressor valve opening ( you'll see the old one there near the front)
6 Insert the new valve with the connector facing harness facing towards the passenger side of the vehicle
7 push the valve in until it seats
8 put the snap ring back in. Valve replacement is complete
9 Receiver dryer - there are simple write ups for the receiver dryer R&R em ail me with questions if you have them
10 check all connections and torques
11 refill the system, in my case 2008 V8 with rear air was 2.31 lbs filled it up, put a thermometer in the vent and took it for a spin them in the driver side vents is 46 degrees. Sweet.
12. Replace Skid plate
13. Drive the vehicle for a bit maybe a week or so and check the refrigerant volume to make sure there are no leaks.

Her are images of the valve and looking up at the compressor from below at the valve aperture with the valve removed. New valve is on the right, looks like they redesigned the part a bit .

 

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Discussion Starter #8 (Edited)
Should I add some A/C oil when replacing the receiver/drier and solenoid? If so, how much?
I bought the receiver/drier from Rock Auto. GPD 1411916
 

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Discussion Starter #9
Maybe just pouring out whatever oil is in the old receiver/drier into a measuring cup and then adding the same amount back into the new one is the correct procedure?
 

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Discussion Starter #10
I tipped the old receiver/drier every which way and didn't get any oil to come out of it. Not sure if I should add any oil to it, but I won't since none came out.
Vacuuming the system now, after replacing the solenoid and receiver/drier. Fingers crossed.
 

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Discussion Starter #11 (Edited)
Vacuumed and filled the system. I screwed up when filling it with freon - left the high side manifold gauge connected and had the valve open. I'm guessing this let refrigerant out the gauge.

Fixed that issue and then continued to fill the system, though I suppose I can't be sure how much refrigerant is really in. I kept adding freon until I got to about 40-45psi on the low side. The high side is about 200psi.

I put a BBQ grill thermometer in the center vent and the coldest it will read is 60F. That's when I'm driving at highway speeds. The outside temp today is about 95F.

Is there anything I can do to get this working better? Am I ahead of the game if I just take it in and have a shop take care of it?
 

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- these are really tricky to service with just manifold gauges also high ambient temperature will affect the fill and pressure readings bear in mind that the fill needs to be done by the prescribed weight to be correct which I why i suggest getting done with a service machine in a temperature controlled shop or jiffy lube it will also let you know if there are leaks. An incorrect fill that is slightly over will adversely affect the performance of the system - too much is a lot like too little there does not seem like there is much tolerance for inaccuracy. The receiver dryer traps moisture so water would come out not oil
 

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Discussion Starter #13
With the system empty, I did the calculations and came up with it needing 37 ounces of freon. I bought 12 oz cans and thought that if I just put 3 cans in, that'd be close enough and I'd be OK. Well, that idea was messed up because I left the high side valve open and probably lost some freon out because of that.

The air in the vent was down to about 55F today when the temperature was much cooler and less humid than yesterday. I think it was in the 80s today instead of 90s. It still does not get quite as cold as it used to, however.

I may have to just take it in.
 

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I took it to the valvoline quick lube down the street from me, explained I needed it evacuated and would be back for the fill. They evacuated the system, I turned off the AC drove home replaced the valve and new dryer then drove back and they refilled it. I have a 7 passenger with rear air which takes a bit more refrigerant than the 5 passenger so make sure they look at the the sticker under the hood and put in the correct amount. I paid 79.00 at jiffylube for the vac and refill. You'll need a pair of snap ring pliers for the ring holding the valve in place there are several o rings which seal the valve a new valve should have them there is a pigtail plug which is easy to remove as well - take the skid plate off the the car and the compressor is the bottom accessory you can see the valve on the bottom of the com with our removing anything else here is what the valve looks like :

I found my steps for this in an old post here ya go-
1. remove metal skid plate
2. push lower radiator hose out of the way and use a flashlight or thin shop lamp to illuminate the area and hold the hose out of the way
2 use a long handled pair of snap ring pliers and remove the snap ring from the valve
3. unplug the wiring harness and remove from the harness plate
4. attach long nose vice grips to the valve or otherwise wiggle and pull it out rotating and pulling with even pressure ( there may be some remaining pressure in the system which escapes/.
5. put new o- rings on the new valve and the large o ring in the compressor valve opening ( you'll see the old one there near the front)
6 Insert the new valve with the connector facing harness facing towards the passenger side of the vehicle
7 push the valve in until it seats
8 put the snap ring back in. Valve replacement is complete
9 Receiver dryer - there are simple write ups for the receiver dryer R&R em ail me with questions if you have them
10 check all connections and torques
11 refill the system, in my case 2008 V8 with rear air was 2.31 lbs filled it up, put a thermometer in the vent and took it for a spin them in the driver side vents is 46 degrees. Sweet.
12. Replace Skid plate
13. Drive the vehicle for a bit maybe a week or so and check the refrigerant volume to make sure there are no leaks.

2008 V8 Sport with similar AC issue. Pressure would spike before dropping down. It would take a while to start feeling cool (up to 10 minutes), but never getting cold.

First try: Took it to the shop, it had over 2.5 lbs of refrigerant. They removed some so the new amount was 2.3 lbs. Started getting cool air sooner, but still not cold.
Shop quoted me $1400 to replace the compressor and drier.

Instead, I tried the compressor control valve and receiver drier and it seems to have worked. I can't tell yet, because it's only 75 degrees outside, but it definitely started cooling a lot quicker and seems to be colder.

Got both parts from FCP Euro for $185 delivered (OEM valve, ACM drier).

Followed instructions above, and they were very helpful (very nice write-up). Here are few things I would add from my experience. Make sure you remove all the refrigerant before you begin.

1. skid plate: there are a total of 6 bolts on mine. i had to attach a pipe to the wrench handle to get enough leverage to get the bolts off. then it was just a matter of pushing the front portion up to dislodge and then wiggling and forcing the plate forward against the bumper to be able to slide it out.

2. Make sure you have either very short or very long "internal" snap ring pliers. Anything else, you're wasting time. It's a very tight spot to get to the snap ring that holds the valve in place, so you either have to reach from outside with long snap ring pliers or get behind the radiator hose with very short ones. The main problem is the radiator hose. Maybe you can rotate the snap ring to a better position so you can have an easier time with it (I didn't realize that until after).
After trying snap ring pliers of different lengths and wasting time, I ended up bending the handles on a short one to make it ever shorter. Finally, I succeeded in getting the ring off.

3. There's a screw holding the valve wire to the compressor with a clamp. It's easier if you remove this screw first. This screw holds more than one thing, so just remember how it all goes together.

4. I put the "L" ends (90 degrees) on the snap ring pliers, which allowed me to latch them on the the indents on valve (look at the black part of the new valve, you'll see what i mean). Then it easily pulled out, the remaining pressure pretty much did the work; I just had to pull a little.

5. the hardest part was getting the old large o ring from the opening. I used a needle point to grab it and pull it out.

6. my old valve wire was facing down, so I put the new one the same way.

The rest was pretty straight forward.

For the receiver drier, it looks more complicated than it is.
-Remove the passenger headlight.
-Then disconnect the wire toward the bottom of the drier.
-Use the holes on the new drier to figure out where the screws are. If I remember correctly, I think there are a total of 3 screws. One on the front, one one the back, and one on the bottom. They're all different sizes and types. So make sure you have the right tools before you begin. The bottom screw is a large torx, maybe T27?
-After you get all the screws off, pull the plastic shield out of way, and it should just pull up and out. Transfer the connector from the bottom of the old drier to the new one with new o rings if you have them (mine didn't come with them). Then transfer the screw clamp from the old drier to the new one.
-Put everything back and connect the wire. Put the headlight back.

Put the Skid plate back (required some wiggling and pushing the bumper cover quite a bit, but it did go into place).

Pressure tested and refilled at the shop ($89).
Already feeling colder with ambient 75, but I will test later today in 90 degree weather.
 

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Very cool, will book this one for future reference. Thanks for the update!
 

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Okay, so I am having a similar, but slightly different problem and I have a few questions:
-first, my A/C (on an 07 V8) will be pretty weak (ambient temp), then will decide at some random time to start putting out cooler air. Note that I said "cooler". It's not cold really... just cool. What's slightly different (than the experiences above) is that I cannot see a clear correlation to it blowing cold after the car has been sitting (and is presumably cool). e.g. Sometimes it will simply decide to on the interstate after it's been running for 30 minutes or an hour. It does not seem to be cold immediately on startup. Does this sound like it could be compressor control valve? For what it's worth, it's gotten progressively worse over the last month... from being an occasional problem, to being more frequent, to now not really working at all.

-Second: Not to ask a stupid question, but where is the high side valve? I have a manifold set and would like to check the readings (even though I know it might not help indicate the bad compressor valve) Can someone tell me where the heck the high side valve is?

-third: I measured the low side with a cheapie gauge that came with an r134a bottle. It measures way high for the low side. As in: way into the red. This was with the AC switch turned up to max, but I am not absolutely certain that the clutch was engaged. (esp per Peter's statement that you cannot visually tell that the clutch is engaged). So the question is this: What (if anything) is the significance of the low side being so high? Is this an indicator in any way of the compressor valve problem? Is a low side reading indciative of anything at all if the compressor is not running? and yes, I know that it might mean that it is actually overcharged, but we've had this car only about 3 months, so I don't know if it was ever overcharged previously or not.

thanks, all!
dan
 

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@drsides Yes, this sounds to be the control valve. Inconsistency is the key. These valves stick which can cause all sorts of things to go wrong. Gauges don't really help you with diagnosing these cars since they don't always move the same amount of refrigerant all the time. Just because the high side is really high doesn't mean it is overfilled, it could mean that the valve is sending too much refrigerant through the system than the ambient temp calls for.

As for the high port location, it is on the top of the receiver/dryer in front of the radiator (passenger side).
 

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percavman;5651985 Just because the high side is really high doesn't mean it is overfilled said:
Great info. Thanks so much. But to be clear, did you mean the LOW side being really high? (That is what I was asking about).

thanks all! This is great to hear all of this information. I feel like I know what I need to do now. Now I just need to find the best price on the control valve and drier!

In a related note: It's so nice to be in an automotive forum where people are polite, helpful and respectful of one another. Other forums that I've joined can be technical, but can be infected with sarcasm and even name calling. It's very nice to be on a forum where one can ask questions without fear of being mocked.
 

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Yes, high pressure readings on the pressure (low) side indicate a compressor issue (e.g. valve).

I am just glad to help however I can. Welcome to the forums and enjoy your Volvo!
 

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percavman;5651985 Just because the high side is really high doesn't mean it is overfilled said:
Great info. Thanks so much. But to be clear, did you mean the LOW side being really high? (That is what I was asking about).
My low side would spike really high initially (60+) and then drop down to 30-40 and My guess is that's when it started to blow cool air (took up to 10 minutes).

After changing the valve and receiver dryer, it's working great. Cold air within seconds. We took a 500 mile trip driving between 60 and 110 degree weather and the AC never faulted. The wife never wanted to ride in the XC before because it was always hot. On this trip, she had to turn on the seat heater in 100 degree weather because the AC was too cold... imagine that!
 
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