850 AC Compressor Installation

Decapod10 · Post by **Decapod10** » 28 Jun 2011, 20:13

I am in the process of replacing the ac compressor on a 1996 850. The compressor arrived without lubricant. Information received indicated that the compressor needed to be charged with 6.8 Fluid Ounces of oil. Dutifully I poured 6.8 Fluid Ounces of oil into the compressor through one of the ports. Keeping the oil in the compressor without flipping the car over on the passenger side presents a challenge. The whole process has now left me concerned and uncomfortable. I would appreciate it if someone could enlighten me as to how the installation process is suppose to work. Thanks!

Post by **Juan62** » 29 Jun 2011, 00:42

I would start at the top of this forum above, Repair database...lots of info there.

copandengr · Post by **copandengr** » 29 Jun 2011, 02:13

When a compressor is recieved saying it needs a certain amount of oil, they are not talking about pouring the oil into either the high pressure port or the low pressure port. A compressor is almost like a miniature engine. If you look on the body of the compressor at the top and in the middle of the body, you will find a nut that looks like a regular oil drain plug..This is where the oil goes. Some compressors are shipped wet, meaning the oil is already inside the pump. You should have had an instruction paper in the pump's box that will tell you where the oil should be poured and also show dimensions and a drawing to make a dipstick for that particular pump. If you did not find this paper then return to where you bought it and ask them to get you the proper paperwork.

My advice would be to flush the entire system which would require removing the dryer/ receiver (replace the dryer do not try to reuse it) and the orofice and then adding the proper amount of oil to the system including filling the pump with the proper amount of oil. Think of the oil you pour into the compressor like the oil pan of a car engine and the oil you install into the rest of the system as a top end lubricant for the compressor's pistons and valves. Attempting to flush the system with the orofice removed will stop it up.

Also, make certain you are using the correct type of oil. Most cars made after the switch over from R-12 to R134A use PAG oil.

There should alsop be a sticker somewhere under the hood telling you the exact amount of refrigerant to put in. Overcharging will cause extremely high head pressure and will very quickly ruin your new pump or burst a hose or some other part of your A/C. My advice would be to shell out the bucks to have a professinal do this repair. It sounds to me like you are not too familiar with A/C service. To do this properly requires a very expensive set of gauges along with a vacuum pump and refrigerent scales to weigh the amount you are putting in. If you do not have these I would not even attempt this repair myself.

Post by **precopster** » 29 Jun 2011, 08:50

I have to second that last post. Sure assemble everything to save some dollars, but you will need a new receiver/drier and orifice tube which both require a special tools to remove. Then take it to a refrigeration mechanic for a vacuum and refill. Any moisture in the system (ie any air that has entered the system) will almost certainly begin to slowly kill your new compressor if the system is not evacuated.

Post by **erikv11** » 29 Jun 2011, 09:06

Orifice tube requires only common hand tools to replace. Open end wrenches. Receiver/drier requires one specialty tool, to release a spring-lock connector.

However, replacing the drier is a very unpleasant job just because of where it is located and the difficulty of getting the wrenches onto it. The spring-lock release is pretty easy to get at. There were some recent posts about how to do it.

petek153 · Post by **petek153** » 29 Jun 2011, 18:43

I'm doing the same repair the compressor arrived with oil already in it but noticed the original looks like a pressure relief valve in it but the new one looks like it was never taped for one. It was listed as oem new from FCP did anybody else notice this not there on replacement ones?

Decapod10 · Post by **Decapod10** » 29 Jun 2011, 20:33

Thanks for all the inputs. This is the base element on the front side of the engine. I am in the process completing the replacement of the engine and wanted to make sure that I took care of everything on the way up as I reassembled everything. This just one of three volvos I currently own the others are a '98 V70XC and a '99 S70. The dealers (meaning 3) have repeatedly demonstrated that they don't know squat about the AC systems on these cars, so I approaching it with a consensus of opinion.
Thanks again for the inputs.

Post by **erikv11** » 29 Jun 2011, 23:08

The orifice tube/valve is super easy while the engine is out, if you haven't dropped it back in already ...

1. Remove vent piping from cabin to ECU box (couple torx screws at firewall, sections just separate)
2. Locate the hard orifice tube AC line, it is the hard AC line closest to the fender well. On the line there is a large connecter, I think one side is 19 mm the other is like 16 mm. Can only get at it with box wrenches.
3. Loosen distal mount of of that hard AC line. You need a hex key socket, like 6 or 7 mm and a short extension, the socket head cap screw is up near the passenger headlight. Not the one holding tubing together, the farther one that is a mount.
4. Once the pipe is loose, unscrew the two halves of the hard line, the orifice tube is in there. Note orientation.
5. Take new orifice valve, dip it in proper viscosity PAG oil (great post on this site from Ozark Lee about proper PAG weights for different compressor models), align in proper orientation (O-ring side to the firewall), slide orifice valve into tube. Orifice will stop when it hits a notch, the end should be just inside the tube recess.
6. Reassemble: hard pipe nuts, then distal hex mount, then ECU vent pipe. Done.

EDIT: note I said "when engine is out," i.e. this assumes AC system is already exhausted (no R134A in the system).