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Volvo 850 a/c system: what to do, what not to do

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JimBee
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Volvo 850 a/c system: what to do, what not to do

Post by JimBee » Mon May 29, 2017 10:41 am

I like the idea of "weighing in" refrigerant, as abscate has suggested, though I haven't tried it, yet. It would be helpful to have a detailed stepwise description of this process.

Most of what I have learned is from various MVS posts with a few from other forums and local technicians. I still feel like a neophyte, but more confident than when I started. Hopefully, others will chime in with technical corrections and we'll end up with the best guidance in one place.

From talking with a couple of service techs in my area, and viewing You Tube videos, I'm aware of warnings of systems being damaged due to overcharging, which I might have done. Plus, I was shaking the can to fill the system. That's actually in the instructions on the can. But I read somewhere that can liquify the refrigerant causing a problem. Voices of experience on how to do this safely, while also considering whether the system has enough oil, would be helpful. Jimmy57, Ozark Lee and abscate and a few others have provided a lot technical expertise on these systems. I'll link some of those, too.

Wouldn't it be great to have a sort of definitive thread (all in one place with topical sections?) for DIY'ers on keeping the aging a/c system alive and chilling us out. Some of the other threads on the site would definitely work well here.

Suppose we begin with the #1 absolute safest way to ensure a proper and safe restoration. From what I've been learning recently, that would entail having the system professionally pumped out (if there's any refrigerant still in it), then remove and replace the dryer, and its o-rings. That's a separate post—it's not easy but can be a lot easier than trying to disconnect it by reversing how it went together. I needed to replace my compressor, so taking it off wasn't optional.

So short of going into the dash to replace the evaporator, refurbing things under the hood would begin by removing the compressor. The alternator will need to be out of the way (for the compressor, 4 14 mm bolts and 6 mm hex (Allen) key for line flanges). I found that removing the cooling fan and shroud and setting the power steering pump up on the intake manifold opens up the space making the job easier. I placed a sheet of corrugated cardboard across the the radiator for protection.

Hold the compressor, open ports down, over a drain pan and turn the clutch several revolutions in each direction to get most of the oil out of it. Check the pulley bearing and replace if noisy (I did that). They can be found for around $18.00 on ebay.

To remove the pulley, the clutch needs to come off first. Autozone has a kit (for rent) that contains the round aluminum disc with 3 slots for screws. Get 3 ~ 25 mm x 5 mm screws, with washers, and thread them through the disc into the threaded holes in the clutch face. Also get a longer 10 mm (socket size) bolt to use in place of the OE center bolt (I think the one I used is 20 mm). Partially screw in the new center bolt and the arbor bolt that's used with the puller disc will push against the head of the new bolt. You might need to unscrew the center bolt as the clutch off so it doesn't bottom on the center bolt.

DO NOT thread longer screws through the clutch face to bottom them out to push the clutch off. It does come off that way, but the screws bottom out on the bearing seal and ruin it. I know from experience. That's why I replaced my pulley bearing.

If the compressor pulley is removed, you will have removed the circlip that goes in front of it on the nose of the compressor casting. That should be renewed. Clean its groove thoroughly while the pulley is off. Reinstalling the pulley you'll want to be careful not to damage the bearing seal. I found that a stub of 1 1/2" PVC pipe can be used to tap it on. Actually, I started driving it on by hammering on a wood block that spanned the bearing. Then finished with the pvc pipe as the power shaft came through the bearing. It does take some force. When the pulley is seated far enough back to reveal the circlip groove, I installed a new circlip and then reused the pulley puller tool (auto supply stores rent it out) back on the pulley to snug the pulley forward against the clip. Mine moved about .5 mm.

Of course, check the clutch clearance, setting the gap at about .3 mm (about the thickness of a sheet of paper). I did that, removing the thinner of the 2 shims at the end of the power shaft.

I cleaned up all o-ring surfaces using a 3-M type non-scratching scouring pad and o-ring grooves with a tooth brush.

PAG OIL. The Volvo 850's got several different Zexel compressors, according to the dealer parts tech I consulted. Apparently the o-rings on some were different. They all have a badge that states oil requirements. Mine indicated 200 ml of oil. The Volvo service tech I talked with said to assume there will be 10-20 ml left in the condenser, lines and evaporator. Then divide up the remainder between the new dryer (~ around 50 ml, or 50 cc's) and ~ 140 ml into the S (suction) port of the compressor.

New dryers are capped to keep moisture out. Leave the caps in place until you're ready to install the dryer. REMEMBER to put oil into the dryer before you install it. Thread on the suction hose, aligning, by sight, the edge of the hose parallel with the dryer's gooseneck. With a new o-ring on the hose fitting, tighten the hose firmly onto the dryer. You won't be able to this once the dryer is installed; there's no room to get a wrench on it. You'll still have a plug on the end of the dryer's gooseneck, so that's tight to air. I put a baggie over the compressor end of the suction hose secured with a rubber band until I was ready to bolt it up to the compressor.

The garter spring in the springlock cage should be replaced. The new dryer I bought came with a new one, plus some o-rings for the dryer connections.

Hold the compressor open ports up and turn the clutch a bit to circulate oil in the compressor. Gently, some oil will burp out. Wipe off any excess. Use a piece of packing tape to cover the ports while you reinstall the compressor. I installed the compressor before the dryer.

With fresh oil, new o-rings and things cleaned up, some potential leaks and problems with correct oil volume are eliminated. In my case, I had to replace the compressor ( I installed a used one ), so the other details didn't require a lot of extra work.

I still need one o-ring that's a better fit than one I used. When I have them all, I will measure them (diameters and thicknesses) and post. The Volvo tech I talked with told me they don't have the exact spec'd o-rings for those compressors, so they just match up what they need from a kit. O-rings designated for a/c systems are labeled "HNBR rubber".

I have some pictures that I'll include, after I've taken a few more.

Having been through this once, I wouldn't hesitate to do it all again, which I might need to if my other 850, which I know needs a dryer, has any other leaks. I'll probably replace all the o-rings at the condenser and compressor, anyway—in addition to those involved with the dryer.

I didn't replace the orifice tube because of the difficulty of disconnecting that line. Hopefully, that will not cause a problem.

Unless other leaks have been identified, these updates should help a lot to get a system back on track.

Comments?

Next best fix (short of adding "stop-leak") ?
Last edited by JimBee on Mon May 29, 2017 7:32 pm, edited 1 time in total.



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Re: Volvo 850 a/c system: what to do, what not to do

Post by Ozark Lee » Mon May 29, 2017 6:40 pm

To weigh it in you really need a refrigerant scale to do it accurately. Those typically are not for rent but if you are buying the small cans of R-134A you can guestimate close enough. A full can of the auto parts store stuff is 12 oz and the system capacity for an 850 is 26.2 oz - 2 full cans plus an extra shot out of a third to get it closer. The bad thing about using 1/10th or 2/10ths of a can is that the cans will rarely seal and the rest of it leaks out. I buy R-134a in 30 lb jugs and I weigh it in with a scale that has a 200 lb range but it has .1 oz increments - you can get it spot on. The big jugs seal very well so you don't get the loss. I didn't really buy the scale for automotive work but rather to service the central air units at my rental properties but it works just fine for the automotive stuff. The Snap On scale is just a rebadged TIF scale that the HVAC guys use. Any scale with 0.1 oz resolution will work.

For oil, filling the filter drier is a mess so I often just by the PAG oil that is mixed with 134a under pressure and shoot it into they system first through the low side service port. That type of oil has a couple of oz of R-134a so you need to deduct that from the rest of the charge. The label on the can will clearly state the amount of oil and the amount of refrigerant in the can. I put it in as a liquid, top down on the can, with the system not running since the oil does not vaporize. If you do it with the system running there is a slight chance that you will hydro-lock the compressor. Once it is in there the liquid refrigerant will vaporize very quickly unless you are doing it on a subzero day and the time it takes to walk around and start the car is sufficient. With the system under vacuum the refrigerant wants to go to the filter drier anyway since it also acts as the accumulator.

In general it is best to add R134a as a vapor but it takes a good long time. I get impatient and I often give it small gulps of liquid with the compressor running until it is charged. You can stick the refrigerant can in a pan of hot water to speed things up when charging with vapor.

...Lee


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Re: Volvo 850 a/c system: what to do, what not to do

Post by JimBee » Tue May 30, 2017 10:31 am

Lee,

Thanks. This is helpful. Your post helps to frame some other questions I've been thinking about.

You mention when the "system is under vacuum", so I guess you're referring to a system that has been evacuated. Yes? Does evacuation remove the oil as well as refrigerant? If not, are we back to the same question about how much oil is actually in the system after evacuation?

Am I correct that you're referring to replacing oil lost when you changed out a dryer then pumped it down? Two ounces of fresh oil would be about 60 ml. But, without emptying the compressor, is there a way to fairly accurately estimate how much total oil would then be in the system?
What can we safely assume?

If the can isn't shaken, top side down, will all the contents eventually flow into the system?
I think my clutch was cycling while I was shaking the can and that's when the compressor locked up. After that happened, I read somewhere and a local Volvo owner mentioned, it's safest to just spritz in a little, wait, then a little more. Is that being unnecessarily cautious?

Is it true that the engine rpm's should be around 1500 when charging the a/c system; if done at idle, system could build too much pressure at normal driving rpms.

Also, is all refrigerant the same? Reading labels at Walmart, I noticed that the lower priced brands are made in China. But the higher priced, more designed cans, are "product of USA and China". Is there likely to be any difference?

I have this digital kitchen scale that is supposed to measure weights in small increments. So, using this scale, I would weigh a whole 12 oz. can and assume that when it weighs 12 oz. less that all the contents have been dispensed. Then the 18 oz. can. I would only want to reduce its weight by about 14 ounces. That's it? That's how to weigh it in?

https://www.amazon.com/DecoBros-Multifu ... chen+scale



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Re: Volvo 850 a/c system: what to do, what not to do

Post by Ozark Lee » Tue May 30, 2017 5:09 pm

Very little oil, if any, is lost via the vacuum pump or even with a recovery machine if the vapor is recovered. Vapor recovery is about the only option with a Volvo since there is no high side service port. The procedure is to:

A) Recover the refrigerant. If the system is flat this step isn't necessary since there is nothing to recover. I always try to recover what I can and recycle it back into the system. That is a perfectly acceptable practice so long as it goes back into the car that it came out of and that it isn't being recovered from a car that had the compressor grenade on it. In the case of a compressor failure the refrigerant is contaminated it shouldn't be reused. Refrigerant recovery requires a recovery machine and a recovery tank and that isn't something that most people have laying around. Most shops will recover the refrigerant for a nominal fee but in that case it is just gone since it goes into a common recovery tank mixed with refrigerant from other cars and you don't know what the background on each of the recoveries is.

**Venting any refrigerant to the atmosphere is a violation of EPA rules.**

As a practical matter, unless you are Section 608 or 609 licensed, there is very little the EPA can do about it. As refrigerants go R134a is one of the least harmful to the climate since it is a HFC refrigerant and it has zero impact on the the ozone layer. That said, it is always preferable to have the refrigerant recovered and properly disposed of.

B) If the system has been at or near zero pressure for any period of time more than a few hours you should replace the filter-drier. On a Volvo it is a challenge but the way I do it is to unbolt the bracket, use the quick release tool to release the spring clamp, and then rock the filter drier back and forth until it comes free from the tube. At that point I drop it down so that I can get to it below the bumper to get the big nut loose and unscrew the line. Two people working the wrenches isn't a terrible thing since the nut is normally very tight.

C) Replace the O rings on the filter-drier fittings and reinstall that filter-drier. Getting it back together is much easier than getting it apart.

D) Pull a vacuum on the system and monitor the vacuum level for a period of at least 30 minutes to make sure the vacuum level does not rise. I use a micron gauge to pull a 500 micron vacuum but you can do it with the gauge set by getting the vacuum level to at or very near a level of 30 inches of mercury which is the way a standard manifold gauge set is indexed.

With the system at vacuum it will effortlessly suck in the just about the first can of refrigerant or more and then you can turn the system on to draw in the the rest of the refrigerant up to the required weight.

If the can says R134a it should all be chemically all the same but I suppose you never know. I think I used to buy the Interdynamics brand at Walmart and it is the same as most of the auto parts stores and I have never had any trouble with it. Short of testing it with an ARI-700 purity testing machine (about $2000.00) you just have to believe the can.

A kitchen scale should work fine. If it will zero with the can on it then that is perfect but otherwise just note the starting weight and the amount of refrigerant is the starting weight minus the ending weight. The contents on the can label should be a net refrigerant weight rather than the gross weight including the can itself but you can verify that with the scales. Have the hose hooked up to the can to note the starting weight.

The only other technique thing is the way to remove the gauge hoses. On a system where you are watching both the high and the low side I remove the low side hose with the system operating and then turn off the car and let the pressure equalize before removing the high pressure hose. You lose less refrigerant disconnecting that way. On a Volvo with the low side only I remove the blue hose with the system running. The Schrader valves are pretty quick and the unintended release is minimal but the less the better.

...Lee


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'96 Platinum Edition Turbo
'99 V70XC - Nautic Blue
Previous:
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

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Re: Volvo 850 a/c system: what to do, what not to do

Post by JimBee » Tue May 30, 2017 8:08 pm

Coverage in these posts is really helpful. I'm sure many will appreciate the thread, and I certainly do.

We might as well cover "turning the system on" (assuming the clutch is properly set):
"With the system at vacuum it will effortlessly suck in the just about the first can of refrigerant or more and then you can turn the system on to draw in the the rest of the refrigerant up to the required weight."

Related to the above: Can you include a comment on the engine rpm's during a/c charging? I seem to recall in earlier posts that engine speed should be at least 1500 so the charge will calibrate to a fully pressurized system, rather than a less pressurized system (engine idling) that then becomes overly pressurized at normal operating rpm's while driving.

Many thanks!
Jim



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Re: Volvo 850 a/c system: what to do, what not to do

Post by abscate » Tue May 30, 2017 9:05 pm

It will suck in at idle, but what many do, including me, is evaluate temperature delta while filling. I aim for 40 F temp change at 1500rpm, recirc, blower on high. 40 F delta is really good, 35F is pretty good.


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Re: Volvo 850 a/c system: what to do, what not to do

Post by sleddriver » Wed May 31, 2017 9:40 pm

Interesting thread JimBee! Thanks for posting.


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Re: Volvo 850 a/c system: what to do, what not to do

Post by JimBee » Thu Jun 01, 2017 11:06 am

sleddriver: I'm glad you're finding this helpful. I certainly am, too.

abscate: so can we put to rest what I thought was a requirement that we charge at 1500 rpms, for the reason I noted above?

And, keeping with the title of this thread, what are some things Not to do when getting the a/c system up to snuff?



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Re: Volvo 850 a/c system: what to do, what not to do

Post by abscate » Thu Jun 01, 2017 11:32 am

JimBee wrote:
Thu Jun 01, 2017 11:06 am
sleddriver: I'm glad you're finding this helpful. I certainly am, too.

abscate: so can we put to rest what I thought was a requirement that we charge at 1500 rpms, for the reason I noted above?

And, keeping with the title of this thread, what are some things Not to do when getting the a/c system up to snuff?
Correct - filling at idle will just take longer. You do have to evaluate the performance with the compressor above idle, though. See Jimmy's post on that. Hot water bath for the can will speed the charge a bit. I have had cars take 30 minutes to fully charge - it isnt an all day affair.

No liquid into the compressor, bad.

Hand and eye protection.

I often find the thumbscrews on the manifold loosen if I twist the hoses.

Dont waste time looking for the high pressure port on a P80 - you don't have one!


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Re: Volvo 850 a/c system: what to do, what not to do

Post by JimBee » Thu Jun 01, 2017 3:17 pm

I found a couple of posts that I think rounds out this discussion.

Here, mcp details how he topped up his system with refrigerant. He notes that the compressor must be running when topping up. He noticed, like I did that if it isn't running, the gauge on the refrigerant can will read in the red / danger zone. I presume that's because it's registering the pressure that's in that line which drops sharply when the compressor is pulling a draft on that line. He notes some other details that are also useful.
viewtopic.php?t=30971

Ozark Lee further explains why the refrigerant can gets cold and how that affects its release of refrigerant into the system. When I was charging my system, I had to stop and let the can warm up a few times to start flowing again.
Ozark Lee wrote:
Sun Sep 01, 2013 4:04 pm
As you charge the system the pressure drop in the can causes the can to drop in temperature. As the temperature decreases the flow of the refrigerant slows, in some cases nearly to a stop. Once the can heats up again the pressure increases, even if there is a very small volume of refrigerant left in the can.

The can is not only at 45 PSI when it is fully loaded, its pressure can be much higher depending on the ambient temperature.

Just slowly unscrew the can and throw it away, there won't be much that comes out of it.

...Lee



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