A/C Leak Question

[LifterEyes]

It's about time that I get started on getting the A/C working again on my 944. Apparently the system has a leak in it. I found a copy of a test done at Midas some time ago and all it says is: "Major Leak W/AC - Compressor + O-Rings." I know that the front seal on the compressor is bad and plan on replacing the whole compressor but I am unsure of what O-Rings need to be replaced. Naturally I am going to replace the ones on the compressor when I replace it and the O-Rings on the drier as well.

In anyone's experience, are there any other seals that commonly go bad that I should replace before I go to have It tested and charged?

[SolReaver]

Take a black light to the AC system and see if you can find where the PM spotted the leak. Systems are usually tested with a phosphorescent dye in the Fluid. where it leaks out there will be some dye and you can spot it with a black light. If it was tested a while ago then the dye may have rubbed off and you have to add it and Pressurize the system again. Another way to test is for a technician to vac it out and see if it holds vacuum. However, that doesn't tell you where it leaks, just if it does or doesn't. Ask the technician to have it hold vac for a while as this cleans out the system by evaporating water.

Hopefully your system has not been open to the air as that causes problems. I would the AC pump seals and the condenser seals as they are reasonably easy to get to. Have a technician vac out the system before hand(if there is anything in it) to not release freon. then have the tech test it. If it holds vac....fill her up and cross your fingers.

[John_AZ]

Originally Posted by LifterEyes

It's about time that I get started on getting the A/C working again on my 944. Apparently the system has a leak in it. I found a copy of a test done at Midas some time ago and all it says is: "Major Leak W/AC - Compressor + O-Rings." I know that the front seal on the compressor is bad and plan on replacing the whole compressor but I am unsure of what O-Rings need to be replaced. Naturally I am going to replace the ones on the compressor when I replace it and the O-Rings on the drier as well.

In anyone's experience, are there any other seals that commonly go bad that I should replace before I go to have It tested and charged?

I replaced my AC compressor-1987 924S Nippondenso w/6 groove pully with a rebuilt from eBay for $225. I have seen them since for about $200 (off season).

You have to replace the receiver/dryer ----and the "O" rings with a new compressor. TIP-unplug and install this last so as not to foul the internal dryer material.

You should flush ALL the hoses, evaporator and condensor. You need new seals.
You should not flush the expansion valve---------unless you have too

AutoZone has a small kit for $5.99 which should be enough "O" rings. I used the Pelican kit with all the conversion valves and "O" rings needed

Pelican Parts - Product Information: 55-9807-901-M325

All this being said, You could possibly get by with just a new receiver/dryer and the seals from AutoZone with your new compressor. This is what I would try first.

Important Use the correct AC oil for the freon you plan to use. R12 oil is not the same for R134a.

Even though products like Freeze12, R22, IceBallCold freon work, I do not recommend. They are flamable and once used, many AC shops will not work on your car. It may ruin or contaminate the equipment.

Search for member mattdavis11. He has a lot OJT knowledge.

GL
John_AZ

[LifterEyes]

Originally Posted by John_AZ

Important Use the correct AC oil for the freon you plan to use. R12 oil is not the same for R134a.

GL
John_AZ

I'm planning on using the rebuilt compressor kit from 944Online and I noticed it says "Compressor comes filled with Esther oil which works with both R12 and R134A." Will this oil truly work for both types of freon?

[John_AZ]

Originally Posted by LifterEyes

I'm planning on using the rebuilt compressor kit from 944Online and I noticed it says "Compressor comes filled with Esther oil which works with both R12 and R134A." Will this oil truly work for both types of freon?

Yes, Esther oil is compatable with both R12 & R134a.

texasblake did a complete conversion and posted it on his website. There may be useful information when you put in the rebuilt compressor and dryer.
A/C Retrofit - Porsche 951 - www.texasblake.com

I would also consider flushing out the condenser if you do no other flushing. The old PAG oil settles at the bottom of the condenser. This can cause a restriction in the freon flow and poor cooling. It is just 2 more "O" rings (AutoZone kit). This will remove any dirt and sludge (compressor chunks) built up after 23+ years of servicing

Always put AC oil on the "O" rings to avoid a pinched "O" ring when installing.

The rebuilt compressor will have Esther oil inside. The receiver/dryer should take and additional ounce. Check to see if the compressor has enough oil installed for both. If you do flush the condenser, you should also put 1 ounce of Esther oil in.

If you open up the system again in the future, replace the receiver dryer again. Pelican sells for $11.
Pelican Parts - Product Information: 944-573-943-00-M253


GL
John_Az

[mattdavis11]

I assume that the 87 944 still has the nippondenso 6E171 compressor, if so, find someone to rebuild it or do it yourself. It's just a few seals. I could reseal the compressor if you'd like, just mail it to me. Let me know.

The advice is solid on looking for other leaks. Black, oily residue near any connection or fitting is also a dead give away for a leak. Remember when changing from R12 to 134a you will only charge to 80% of the factory recommendation. Another note of caution, 944 online says that it's ready to be bolted on, I'm not so sure about that. George is a great guy, very knowledgeable, but he has no earthly idea how much oil has disappeared from your system. Fast leaks obviously lose more oil than slow ones. I almost always start fresh, however I didn't on my car because I can guestimate pretty good. At the very least (if you don't flush the system) measure what is in your compressor and drier and put that amount back into the new to you compressor, and never take someone's word that there is oil in a compressor, always check. I've bought new ones that read "contains 5.3oz of pag 46", but there was not a drop other than assembly oil.

Do it right, do it one time, enjoy it for several more years. Check the service port fittings when you get done adapting, new ones sometimes leaks too.

[LifterEyes]

John,

Did you end up charging your system with R-12 or R-134a using the Nippondenso? I want to be able to charge it with R-134a because it seems easier from a maintenance and cost perspective. It looks like Texasblake is using the Sanden compressor which was designed for R134a but that compressor is twice as much.

Originally Posted by John_AZ

I replaced my AC compressor-1987 924S Nippondenso w/6 groove pully with a rebuilt from eBay for $225. I have seen them since for about $200 (off season).

You have to replace the receiver/dryer ----and the "O" rings with a new compressor. TIP-unplug and install this last so as not to foul the internal dryer material.

You should flush ALL the hoses, evaporator and condensor. You need new seals.
You should not flush the expansion valve---------unless you have too

[John_AZ]

I used R134a (WalMart $6.79 a can) and PAG 46 oil. 2nd season has started and works fine at 85 degrees so far.
Repeating what mattdavis11 mentioned, I used 24 ounces--2 12oz cans R134a in my system. Not the R12 capacity.

I replaced every seal and even the expansion valve seals. But my underdash blower, evaporator and expansion valve unit comes out in 45 minutes. You are not so lucky.

GL
John_AZ

[mattdavis11]

All compressors are designed to do the same thing, it's the oil and freon that are different, nothing else. I didn't ever flush my lines, I just resealed the compressor and put in pag oil and charged with 134. I know I have two different kinds of oil in the system but it's worked great for 7 years now. Reseal your compressor for $10-15 bucks (at the most) and save a ton. It's not very hard, getting the clutch off the nose of the compressor is the hardest part. Otherwise send it to me, I'll do it.

I have not replaced but a few orings, one at the condenser, and ones at the compressor. That's what, 3 orings? If they don't leak, don't open the system where you don't need to.

[LifterEyes]

I have been thinking about possibly rebuilding the compressor myself and saving a couple of bucks. Is there a way I can route the belt so I can still drive the car while the compressor is out?

[SolReaver]

LEyes: as the compressor is used as a tensioner, you will need a bracket or to shoehorn on a smaller belt as a temporary measure. Check this thread out.


http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/439030-c-delete-belt.html

If that doesn't give you enough info, Clarks mentions the AC delete somewhere (I think) Or, you can do a search in this forum for compressor, AC, Delete, Belt, etc... which should yield something useful.

[wild man]

I have just found that the leak on my 951 was emanating from the high pressure port. Tightening the core with a valve core tool eliminated the leak.

[SolReaver]

Congratulations Wild Man! two smileys for you!
Next time you have the system open, replace the valve.

[wild man]

Thanks for humoring me! Although it is still early yet, I think you just made my day. I haven't opened the system up to the atmosphere yet. But if I do, I'll change the core, and the LP side one also, if it's not too much of a hassle. Maybe I should have mentioned this in the 1st post, but the HP port took at least 2 addtional turns, from where it originally was. This is how I detected the problem: I saw some thick, almost clear liquid pooling on the left strut mount (tower?) that I 1st thought was brake fluid. Upon further investigation, I had determined that it was A/C oil charge. With my ear close to it, I then loosened the plastic cap on the valve, and heard a "ssst" sound emanating from it.

[SolReaver]

Yea, I check the valves as sometimes the AC technicians don' t install them fully. I also check the caps all the time to make sure they don't walk away. A spot of paint on the fittings assures no one will accidentally loosen something.

[LifterEyes]

Hey guys, thanks for all the helpful info so far. I really appreciate it. I've been busy so I'm still in the process of deciding if I'm going to rebuild the compressor myself, or have someone else do it.

Also, one thing I am concerned about leaking is the condenser. Since the system is completely empty, is there a way that i can disconnect it, plug one side, and pull a vacuum on it to see if it holds a vacuum?

[SolReaver]

The vac test is usually performed by an AC technician. You see how long it holds vac and it also evaporates water in the system. Usually you test the whole system by pulling a vac on the low side nipple. ( he he, I said nipple!, he he) If you were to disconnect the compressor, the system is no longer a loop, and you would have to plug the compressor fittings somehow...eh..how about with a working compressor?

[LifterEyes]

There have been a few mentions on here about opening the system to the atmosphere. Since the A/C system is completely empty, I'm planning on taking out the condenser so I can straighten out a few body work issues. Should I be concerned about leaving the system open for any extended period of time? I am planning on replacing the drier when it comes time to recharge the system anyway, which I am assuming is the part you don't want left open to the atmosphere.

[SolReaver]

Do not leave a system open to the atmosphere. Moisture gets in and ruins the components. If you have to take out a component seal the rest of the system.

[mattdavis11]

There will be no repercussions if you flush lines right away and cap them unless you let it sit. An acid is made when you expose a/c parts that have seen R134a, pag 46 and oxygen\humidity. If you let it sit, you expose yourself to corrosive damage. I didn't check to see if you have converted to 134.

If you understand the temperature at which moisture boils in a vacuum, the drier could still be good to go unless the compressor disintegrated and shot metal slivers down the line. You shouldn't flush a drier, and they are cheap, but I haven't changed mine.

Flushing always consists of moving solvent (I like denatured alcohol) the opposite direction of the travel of the oil and refrigerant. Think thumb releases in a timely fashion, when the pressure builds, release away from your eyes and face. Wear protective eye wear.

We are lucky to not have parallel flow, or micro tube condensers.