'98 V70 Replacing A/C Compressor -- Questions

[E Showell]

So, I high-tailed it to Harry's In West Hazelton, Pa. yesterday for some parts harvesting. I managed to score a non-seized A/C compressor which I have cleaned up a bit and will swap into my ride.

Here's the thing: I've never done any A/C work beyond shooting a can of 134a in the inlet port of the system, I've got a lot of questions.

First: Is it possible to replace the a/c compressor without pulling the power steering pump, reservoir, mounting plate and alternator? I had to remove them all yesterday to gain access to the compressor for removal and between a couple tough nuts and a lack of access/failure to have the proper tools, it was about a 3.5 hr. adventure to pull the used compressor.

Second: I will also be replacing the dryer/accumulator and probably the Schraeder valve in the inlet port. I have about 8 oz. of the appropriate PAG oil and know I have to add some to the compressor -- like 6+ ounces and I should add some to the accumulator. Where does the stuff get added, physically to those components? There is no cast in arrow saying "add PAG oil here" and what's the best method for adding it? Syringe?

Third: I have a Harbor Freight vacuum pump and set of manifold gauges, but I have never used same and, to be generous, the instructions that come with both are vague and obviously written for someone who has used similar tools in the past and is familiar with the intricacies of their use.

Fourth: When in the process do I add the oil, say, in relation to drawing a vacuum, etc?


Steve-- I had my eyes out for a used charcoal seat bottom and didn't really see a lot that was serviceable, unless you'd be willing to swap in P2 seat, in which case I saw probably one good passenger seat and probably a useable, but on-the-margins driver seat.

Anybody hoping to score a used P80 seat in tan leather or tan skins, I can save you a trip. From current inventory as of yesterday there wasn't anything worth making the trip for.

There's an awful lot of faux wood interior trim bits hanging around in that yard as of yesterday, however.

Any guidance on the a/c fix would be appreciated.

[Ozark Lee]

I am trying to remember if I removed the power steering pump and the alternator when I replaced my son's compressor and I can't remember with certainty. I think that I did do it just from the bottom. The mounting bolts are a challenge but I think I used one of the small pneumatic ratchets to zip the bolts off after I used a wrench to break it free.

Getting the lines off is easy but obviously evacuate it first.

There are two ways to add the oil, as a liquid (which is less expensive) or as a pressurized mixture with R-134A. I have done it both ways but you add it different stages depending on the method. If you add it as a liquid you do it as you install the device and it really doesn't matter which hole you pour it into. The way I measured it in was to buy what is essentially a large eyedropper at the pharmacy that is designed to give children medications. It measures in oz and ml. Keeping the oil from running out while you install the compressor is a bit of a challenge but I just hooked the lines up before I tried to position the compressor. With that method you then pull the vacuum afterwards as a last step before charging.

If you add it in the pressurized form the way I do it is to assemble everything and then pull the vacuum. I then use a charging hose without the manifold gauge set and have the vacuum help to suck the oil into the system. The latter method is much cleaner but when you add a lot of oil like you will with the compressor it gets pricey. If you don't have a dedicated charge hose I would consider buying one. They typically come with an adapter that you will need to pierce the small cans anyway and that may not have come with your gauge set. I really don't like running anything that is liquid through the gauge set since it can mess up the accuracy of the gauge.

As far as using the vacuum pump goes it is very straight forward but I don't know how your manifold gauge set is outfitted. There should be a matching thread on the vacuum pump that is the same as the thread on the yellow charging hose on the gauge set. You simply screw the yellow hose on the pump, push on the blue line to the low side connector on the car, and then turn on the pump and open the low side valve on the gauge. If your manifold gauge set has shutoff valves on the hoses then the valve on the yellow line and the blue line should be open. The low pressure gauge actually reads vacuum as well as pressure (typically in a green background) and it will go down to -30 psi. You want to run the pump for a good 15 to 30 minutes until it is well and truly at -30 and then shut off the valve on the gauge set itself and the pump. Let it stand for 30 minutes or so to make sure that the vacuum holds.

Assuming that the vacuum holds then proceed with charging the system. Since you are starting at zero you should weigh in the refrigerant either with a scale if you have one that will read ounces (just subtract the wight from the starting point) or even by guestimate based on the stated weight on the can and how it feels. You can pretty much feel 1/4 can intervals with reasonable accuracy. I find conflicting information the capacity, 850s should be 36 oz but some of the online charts say 29 oz for the 70 series. I would be inclined to start at 29 oz and see how it does. Adding more is much easier than taking it out.

...Lee

[E Showell]

Thanks Lee. I have three 12 oz. cans of 134a with dye. Should be enough to do a complete refill. I'll see what I can manage on the compressor install. Not happening today since I have to work outside and it is pouring here.

[E Showell]

Lee, did you remove the radiator fan shroud for working access? Some suggest to do so, but I got the compressor out yesterday without doing that and I'd like not to if I don't have to. I did find it easier to get the power steering-related stuff out by removing the thermostat housing and top radiator hose.

[abscate]

Thanks Lee. I have three 12 oz. cans of 134a with dye. Should be enough to do a complete refill. I'll see what I can manage on the compressor install. Not happening today since I have to work outside and it is pouring here.

About 2.5 cans I think, edited bad information hopefully before anyone notices

Screen Shot 2016-07-31 at 12.19.36 PM.png (176.3 KiB) Viewed 1016 times

[E Showell]

Yep. Thanks, Steve. I seem to remember you posting this, or something similar, on a prior a/c thread and that's why I went with three 12 oz. cans of Arctic Freeze for about $12/pop at Harbor Freight when I was in there last.

[cn90]

I just replaced the AC Compressor for my 1998 BMW 528i and wrote a detail DIY in the link below.
The link includes instructions on how to use the vacuum pump or the gauge set.

You will find many similarities to your Volvo.
- Just make sure you use the correct PAG oil for the compressor.
- Correct amount of R134a etc.

Otherwise it is virtually identical.

Here you go the BMW compressor DIY:

http://www.bimmerfest.com/forums/showth ... p?t=924320

[E Showell]

Thanks so much cn90.

[cn90]

Make sure you set the clutch gap properly before installing the "new" compressor from the junkyard.
This way you don't have to play with zip tie, bread clips later.
I posted info on how to fabricate a "puller" in forum (to pull the pulley off the compressor).

[E Showell]

So I've been through the helpful materials cn90 was gracious enough to link to and I still have a couple lingering questions. The "Erik the Car Guy" video on using manifold gauges/vacuum pump was helpful, but assumes a system with both high and low pressure ports. As I understand it, our cars only have a low pressure port. Does that fact change how one goes about using the manifold gauges? If so, how?