John_AZ

Scott,

IF you need to draw a vacuum again, go the the hour or more. The vacuum not only tests for leaks but it is to remove moisture in the system when opened. Moisture will react with the oil and cause corrosion and distroy parts.

The guys at AutoZone put all 3 weights of PAG on the same shelf and they get mixed up. If you just grabbed a can it could be PAG 46, 100 or 150. Asking a minimum paid assistant manager or cashier behind the counter what to use is no help.

Get real comfortable with the DIY on the KCWS page. If you did see black like goo come out of the condenser--DarylJ has the answer.

If you decide to start over with more oil. POE 100 would be the best.
A larger local AC shop will have it for sale.

I use a local parts house ---also has an excellent AC forum:
http://www.ackits.com/c/Compressoroi...ssor+Oils.html

FYI--the PAG you have can be cut with water 6 to 1 to make a great coolant for a drill press or lathe

GL
John

Scott at Team Harco

With no experience in this area, I can't really say if I saw black stuff or if it was just dark oil coming out. I'll hope for the best and figure on the worst.

I checked the oil that was used. It was PAG 100. I also attempted to add more freon. Nothing. The readings were as before, pointing to either the expansion valve or the compressor (or both).

So now I will figure on replacing the expansion valve. While I have it out, I will flush things again.

Is there a way test the compressor, or at least clean it out? Maybe flush a couple of ounces of oil through it? What else should I plan on? I am still holding out hope that the compressor is Ok.

We shall see.

Scott at Team Harco

Good news on the PAG. Is that 1 part water or 6?

Great help guys! You're going to get me through this.

944Ross

Does the compressor body or discharge tubing get hot after the clutch is energized for a minute or two? It's hard to believe it is (apparently) pumping zero freon. OTOH the pump shaft could be broken inside the case. If you take the compressor off again, spin it by hand and see if you hear sucking/gurgling noises. Should be pretty obvious.

DarylJ

That might lower sustem efficiency, but it should be just fine. No reason to worry about that and certainly not change it.

Refrigerant. You mean refrigerant.

I know this sounds ridiculous and picky, but Freon is the trade name for R-12. That is the refrigerant that belongs in your car. You are not putting that in there.....you are putting R-134a in it. Because you are replacing what should be in there (Freon/R-12) with another refrigerant (R-134a) you should be very careful about how you describe them in order to get correct advice.

Hang on before going for that expansion valve........

HOW did you try to replace more refrigerant? Static from a can? With the car running and the climate control on AC? With the compressor clutch engaged? What were the high and low readings if/when you did these things?

You are leaving a lot out, and AC is complicated like that in some ways.....but in others (knowing what you should be looking for) is gets easy. Before you go tearing things apart post what conditions you are seeing your issue (or possibly just a perceived issue) under.

Scott at Team Harco

OK - refrigerant.

I tried to put more refrigerant in with the car running, the climate control set to full cold, fan on high and the a/c switch in the on position. I did this at the low side port. The high side was still hooked to the manifold gauge. At no time did the guage go above zero while the engine was running.

The compressor clutch was engaged.

I waited about ten minutes. There was no perceptable change in the mass of the can. I gave up. I turned the engine off and disconnected the refrigerant line (screwed in the valve on the can then unscrewed and opened the release at the car). I reconnected the low line to check pressure with the car off and when running.

Engine off:
Low ~85 psi, high ~85 psi

Engine on, a/c on:
Low ~85 psi, high ~0 psi

Ambient air temp: ~85 F

DarylJ

At a minimum, the compressor is bad based on that. No telling if the expansion valve is also bad until you have a working compressor in there.

You might as well pull and inspect it while you replace the compressor.

Scott at Team Harco

OK - I figured that would be the ultimate resolution. I'll have to look for a reasonably priced compressor. I will get at the expansion valve when things are apart. A cleaning is likely to put things right? Will there be any obvious telltales if the part is bad?

The good news in all of this is that I am learning a lot about A/C. The bad news is that I will not have time to do anything about it for a while. I need to prepare for our biggest rally of the year (Press On Regardless), and insulate a house, and get started building a shop.

I'll be ready to pick up where I left off though, at some point.

Thanks for all the help guys. I'll post again when I make progress. Maybe in three years....

DarylJ

A visual inspection will tell you what you need to know. If either side is full of black junk and you can't flush it out replace it.

67King

Alright, so I am trying to do an R134a conversion on the 968 (92 - the 93+ were already R134a, natch). All the O-rings are replaced, the dryer is replaced, I've got a can of stuff to flush it (will actually do that as soon as I finish posting this).

First question is how the ports are arranged. From what it looks like, the compressor goes to the condensor, then to the dryer, then valve, then evaporator, then back to the compressor. All (generic) diagrams I have seen have the dryer between the evaporator and compressor. The 968 has a port on teh compressor (by hose going to evaporator), as well as a hose on the elbow of the (same) hose. I assume this is the low pressure port? The other is on the valve. High pressure? It is arranged differently from the 944's. If I understand this the way I think I do, that is where they go, but being an oddball year, it is hard to find definitive info.

So here's the big question. I've got an 8oz bottle of PAG 46. If I can't just pour it in the compressor (I've read to do that elsewhere), how do I introduce it to the system? I'm going to have a shop pull a vacuum on it, then charge it. But they'll use a big tank of R134a, which presumably does not have oil premixed. Do I need to put it in the lines throughout the system?

944Ross

Personal opinion, and one echo'd by several techs I spoke to, flushing shouldn't be done unless absolutely necessary (compressor grenaded, etc). It seems to cause as many problems as it solves.

surfdog4

On my 944 (and my current 911), the low pressure port was on the compressor. I've twice now used the kit that has the oil already mixed in with the first (3) cans of R-134...that was all i needed on the 944, on the 911 i had to put in an additional can or two of "regular" R-134..In both cases it worked fine. I replaced the dryer in both cases, but felt better to leave as much of the system closed as possible..i did a small purge with the first freon can to get the air out from where i replaced the compressor, but that was all i did