The wife wants me to get the A/C fixed on the '86 944T/951. It hasn't run in 15 years at least. I've just been toughing it out for the few months of hot weather here. I pretty much am a hardcore DIY, but haven't done much with A/C - although I love to tackle new jobs.

The A/C system has never been converted to R-134A. I've got a vacuum pump and gauges, but have never used the gauges. The pump I use for other things and the gauges were inherited.

Where would you start?

I assume I'll need a new dryer and hoses at least. Is there anything in the system likely to be worth saving?

Is it worthwhile vacuum testing? Should I just buy everything and replace it all?

Any comments would be appreciated.

 

Why has the a/c not worked in 15 years?
Normally, you do not have to replace the hoses when doing a conversion. When people started doing conversions, it was a money making gimmick. But since the a/c hasn't worked in 15 years, I'd be concerned since the oil hasn't been circulating through the system and the hoses could be dryrotted. It's depends on how much $ you want to put into it. When the system is back together, you should always put a vacuum on the system. Let it sit for 15 minutes and see if the needles on the gauges have moved. If they barely drop, then you don't have any leaks, but if they move a few psi or more, there's a leak somewhere.

They make retrofit kits where you just screw on R134a ports onto the R12 port.

Absolutely replace the filter drier. If the compressor is good, I would still remove that and pour a few ounces of Ester oil (better for retrofitting) into it and turn the clutch to work oil into it.

After vacuuming the system and everything checks out, put the correct amount of R134a in there with oil. Should be a sticker behind driver's headlight stating correct amounts.

 

I suppose I just never felt the need to fix it. It probably had a leak and I never did anything about it.

It's "together" now. Would you just check for leaks now?

One site said there wasn't enough room in a 944 to put the adapter on and fill. They suggested that it was possible to fill with R134a using the R12 port. I'm not sure quite what they were suggesting.

BTW, will it just wok with R134a instead of R12 or is another component of some type required?

Yes, this part I know.

What would you do to check if the compressor is good.

I've got links to the amount of R134a and oil, and even a procedure for the 944, I'm just trying to decide how to get to the starting point of a leak free system with a working compressor. I don't mind spending what it costs, but I'd rather not replace things I don't have to replace and I'd rather not break new things (new compressor?) if buying new hoses first will prevent that.

 

I'm in the same boat, except my AC pump is leaking oil, I'm trying to find a resealed kit and rebuild it myself but I haven't had any luck, Let me know what you find

 

Some helpful conversion stuff:

Porsche Tech Bulletin: http://www.the944.com/ac/page05.jpg

All the 944 A/C stuff you could ever need: http://www.griffiths.com/shop/index....cPath=15_16_52

That second link has compressor reseal kits and -134a conversion kits.

 

I vaguely remember there being a rebuild how to on Pelican Parts forum. I would search over on there.

As far as converting your A/C, I would first do a vacuum test see if you have any leaks. If you do then I would first repair that, then move forward with getting a new A/C Compressor. There is a vendor on ebay who rebuilds these compressors and offers a 2 year warranty. The rebuilt compressor and dryer costs around $200. I did this last year and had a shop put in the compressor and fill with R134a. It isn't that cold, but it works. To get the best performance out of R134a you will need a better condensor coil. You can get these from the aftermarket.

https://rennlist.com/forums/924-931-...mpressors.html

There is a complete kit out there with condensor, compressor, and dryer to make your A/C Ice cold.

http://www.griffiths.com/porsche/ac/944ac/

 

While i would start with a rebuilt compressor, At minimum make sure the clutch is free and pull the compressor off, drain any oil out of it, and add new ester oil to the compressor (a must). Install the R134a conversion fittings (IIRC you need a 3/8" and a 7/16" fitting). The 86 turbo ports are high on the lines in the engine bay, so no problems installing them. Low side is the fat line, high side is the skinny line. Replace the 4 seals under the fitting plate, and the seals on the lines and reinstall the compressor. Install a new drier, vac it down for 45 minutes, and let it sit for 45 minutes and see if it holds vacuum. If it does, put in about 2.5 cans of r134a, watching your pressures as you go and see what you have. If you go straight from vacuum, it will suck in the first can through the low pressure port with the car off (i typically put the can in a bucket of hot water to speed it up). Once that is in, fire the car up and add the rest. The compressor should kick on by itself with one can in. If it doesn't, then apply 12v to the compressor wire to fire it up until it will stay running on it's own. There are numerous youtube videos out there on charging ac,

 

I put the griffiths compressor setup on my car, 134. Gets colder than my Toyota Camry.

In your situation I would start by putting vacuum on the system and see if it holds then go from there. No money spent. Porsche Doc has good info about the seals.

 

Turbo 17,

You can do most of the mechanical work yourself. With regard to the later work of 'evacuate, charge and test', you need special (things you are not going to use often) and experience and frankly unless you are really bored its less costly to simply have a an ac tech handle that part of the job.

The first thing to ponder is the 'inside' condition of the compressor. The 85/2 and onward models do not have cylinder sleeves or piston rings, they are more alike the chevy vega engine, and when they wear you can't economically repair or rebuild them (no can but the OEM whom has the parts). My suggestion is to open up the compressor and inspect the shaft where the nose seal makes contact for signs of rust or pitting, ditto on the reed plates, inspect the pistons and bores and wobble plate for wear. If you find the piston's coating is worn or its scratched or the scratches in the bores then you should simply send it off to metal recycling. You can inspect the pulley bearing (simple roll test) and visually inspect the clutch surfaces and coil. After you have done your inspection if all looks good just a seal kit. There are a few threads on Rennlist and Pelican Parts about R&R of the compressor, your model is also like a 84-89 911 in terms of construction.

Hoses do not dry rot with or without oil, they break down period over time.
The 2 hoses you want to inspect on a car this old are the compressor to condenser hose and the condenser to drier hose; the first tends to fail the earliest due to heat and movement. The drier to TEV line has a short rubber section you can inspect, however the last hose, the evaporator to compressor is a pita behind the engine (usually these don't fail that often).

You will want to replace all the o-rings, drier and add refrigerant oil in the process. Ester type seems to mix better than PAG with the old R12 mineral oil that may be hanging in the system; there are opinions on Ester vs. PAG however in our experience during the past 25 years Ester works perfectly.

R134a runs just fine in a 944/951 provided the system is evacuated & charged properly; hence the suggestion to let a pro handle it.

You can purchase R134a conversion kits, Seal Kits, Compressors or Compressor Kits with all of the same from a few suppliers out there, naturally we are one of the many. So do your research here in the forum.

944/951 Air Conditioning Products

Griff

 

Thanks to all for the replies. I've got some great leads and comments. I'm going to start by checking the external appearance of the hoses and then just see if it holds a vacuum. Then I'll check the clutch and internals on the compressor and go from there.

 

Subscribed !
I am in a similar boat .... Although my compressor does spin the clutch wheel does not spin free enough to allow the belt to do its normal thing
Instead it (the belt ) starts to burn and sends off little black soot in the air
There is a grease build up on that clutch wheel so maybe that says something
Edit
The grease I was referring to is not on the pulley so its not that the grease is causing the slipping but may be a after effect of something that has gone south?

 

I checked the A/C and, as expected, there was no pressure in it. I put vacuum on it and it leaked like a sieve. Next I took the A/C compressor out, and I'll be testing the rest of the system for vacuum leaks. If the rest of the system is good, I'll look at the compressor and decide if I want to replace or rebuild.

I've got a question that came up as I worked:

There seem to be three ports into the A/C system:

One is at the front of the car, driver side near the dryer. I believe this is the high pressure port. This one is fairly easy to access.

The second is directly behind the first port, closer to the firewall, also on the driver/left side, but higher up. It's easily accessible - about as easy to reach as one can imagine.

The third is right at the A/C compressor. I believe this is a low pressure port. It's almost hidden and is very difficult to access. Several manuals/guides seem to refer to this port as the correct port for refilling. One guide indicates that if you put the R-134a adapter on this port, there isn't room to attach the refill hose.

My question is: what is the second port? Is it also a low pressure port? I haven't traced out what A/C line it's connected to.

 

Some models have the service ports located in the engine bay on the inside of the LH front fender; I forget the years for the moment. And, the Porsche PET does not show clearly show it.

But, here is the flow of the refrigerant path and the logical places the high and low side service ports would be on any make and model car:

Compressor to condenser; at this point the refrigerant is a high pressure gas.
Condenser to drier; at this point the refrigerant is a high pressure liquid.
Drier to TEV (expansion valve); at this point the refrigerant is a high pressure liquid.
Evaporator outlet to compressor; at this point the refrigerant is a low pressure gas.

High side service ports can be anywhere between the compressor outlet and TEV. So if you find a service port at the manifold on the compressor where the refrigerant hose lines are and the service port is on the 'high side' of the manifold (compressor to condenser hose), then that is your high side service port. If you find a service port on the hose from the condenser outlet to the drier inlet, that is a high side service port. If you find a service port on the hose from the drier outlet to the TEV, that is a high side service port.

Low side service ports can be anywhere between the evaporator outlet and the compressor inlet. So if you find a service port at the manifold on the compressor where the refrigerant hose lines are and the service port is on the 'low side' of the manifold (evaporator to compressor hose), then that is your low side service port. If you find a service port on the hose from the evaporator outlet to the compressor in the engine compartment, that is a low side service port.

 

Thank you. That's exactly where mine is located.

This is where one port is located. It matches the service manual I have. I'm confident this is the high pressure port.

I think this is where the easy access port is located. That would make sense - two ports are relatively easy to access - a hi and a lo. I won't connect anything until I've traced the lines, and carefully checked them in view of your comments and the manuals.

Again, thanks for the comments.

 

Just remember the rules for charging:

By Liquid (can upside down):
Through high side only, engine OFF.
To do this you accurately you need to have a weighted charge scale.

By Gas (can upright):
Through either high or low, engine OFF.
Through low, engine ON.

Always know how much you 'think' you put in,
and use a P&T chart.

Document everything:
1) Type of oil used, how much.
2) Type of refrigerant used, how much.
3) Ambient temperature outside when testing.
4) Low and High side readings at idle when you
think you got it right.
5) Never overcharge.
6) If you now you only got 16 oz in the car and the
high side matches the P&T chart, then you got air
in the system.
7) If your high side matches the P&T chart perfectly,
but you know you got more than the OEM original
spec of refrigerant in the car.... your wrong or
your equipment is wrong.
8) Never, ever, never ever ever, use leak sealants.

9) The 3m's; man, method, materials