a/c systems...

[Razorback1980]

I have a question about the a/c systems on these cars. Has anyone ever converted to the new 134 by buying one of those conversion kits that include new compressors? Are some better than others or are there differences in some. In Houston, a/c runs all year around or real close to it. It's actually 80 degrees here today and this is our coldest month of the year. I have seen some conversion kits including new compressors and was wondering if those make any sense. Mine isn't actually really broken, but it leaks and has to be filled often, so maybe I should put on a new compressor and upgrade to the new freon.

Thanks for sharing your knowledge and experience.

[Eldorado]

new compressor, new lines, and new seals... only way to stop leaks.

[Razorback1980]

Did you use a particular kit from somewhere?

[AA_Ezra]

I've read post's where it was no prob to upgrade to the new freon or whatever it's called but you gotta replace the canistor for sure adn they recomended all new hoses b/c the new stuff is under higher pressure and the old lines may crack. there are kit's that are sold that just replace the o-rings and fitting's that shoudl work but.. the higher pressure thing get's me. Somone else i'm sure here has done it. I know that Denso offer's new compressor's but you might get away with just replacing the Vac cannistor and new lines. I just use the old stuff b.c it's colder anywhoo

[Razorback1980]

Do you use the actual Freon 12 I think it is or do you use some of the replacement freon substitue?

[natey]

I replaced the AC system on my '88 NA about three years ago. I bought the R134a kit from 944online, and had a "professional" install it (everyone but everyone in the area recommended him, anyway...).

First, the installation was very expensive, because the kit included an "expansion valve", which is apparently buried deep in the dashboard, and takes something like 10 hours to get to. Was it really necessary for the conversion? I don't know.

Second, there were problems with the compressor fit. Initially, the new compressor simply did not fit. To make it fit, another mechanic had to grind down the case and one of the extra mounting ears. Then, it started rattling...the mounting holes were a different size than the car's, so the bolt rattled around in the hole, I don't know what the did to fix that. Finally, while driving I eventually noticed the compressor actually contacting and vibrating against the front left sway bar(?) during right turns, requiring more "adjustment".

In short, it took a long time and a lot of money to sort out. I don't think I'll ever have it done again.

[AaronM]

The compressor itself does not _need_ to be replace, though R-134a requires higher pressures to provide the same cooling as R-12.

You _do_ need to replace the receiver/drier and pull a solid vacuum on the system for a few hours to ensure that all of the R-12 oil is removed from the system. R-134a cannot carry the R-12 oil, so the system will go un-lubricated unless you add oil formulated for R-134a. However, if the oil from R-134a and the oil from R-12 mix, they create an acidic goo that not only does not lubricate, but also corrodes the system.

If you're leaking, then it's probably either o-rings, or the compressor shaft seal. You should absolutely fix the leak before doing anything else though.

[Razorback1980]

Thanks for the information Natey, do you know which kit they used...make sure if I do it that I don't get that one. I thought the expansion valve was under the hood, but there is an evaporator in the dash but I can't imagine why that would have to be replaced. AaronM, thanks for your information as well....some I knew but some I didn't. If you use old R-12 parts, it sounds like the system should be completely flushed to clear out the old oil which is cool, I know how to do that. I have heard many say you need to change compressors and many say no you don't. The only thing I have read that supports the compressor change stated that the new freon molecules were smaller and the R12 compressor was more inclined to leak because they were not designed to hold in the smaller molecules. What I don't want to go through though is what Natey had happen to him. I took my 86 and he replaced everything including my savings account, after that I decided I could learn to work on a/c systems and now it doesn't seem to be that difficult and I see a lot of conversion kits out there but I just wondered if they were a great thing or a rip off. Seems like Natey's was a rip off. Anybody have a good experience with one? Thanks again for the information.

[CPorsche]

I had to replace the condensor on my 944. The old one had a leak. I bought the new one from Griffiths. Do a search in Google, put in Griffiths Porsche. They have several items for the 944 ac.
The stock compressor will work fine with R134. The stock rubber hoses will leak R134 and you may have to refresh with a new can every few months.

[natey]

The kit I got came from 944online.com, I think they only sell one "AC upgrade kit". The price seemed reasonable.

I'm not sure if the kit was the problem or not...it may have been, but then again, every other experience I've had with 944online has been positive, so it may well have been installed incorrectly.

Rip off? Maybe. Learning experience? Oh yes. If I had to do it again, I'd probably seriously consider Griffiths, as CPorsche suggests...they've been recommended here before.

[Razorback1980]

Thanks, I appreciate the information.

[CPorsche]

You do not have to change the expansion valve when you convert to R134. I have an 86 that I converted to 134 and kept the old expansion valve, the stock compressor, stock evaporator, stock hoses. I mentioned in the above post that I did replace the condensor because mine had hole in it. I bought the Kuehl super condensor at Griffiths. It cools great, I have to add R134 about once a year. If the Nippondenzo compressor goes bad I will probably replace it with the Kuehl or Sanden compressor. I will also change the hose going from the condensor to the compressor. I believe this is the hose the guy at Griffiths said would leak more R134 because of its design.

If the AC system currently has pressure then I would remove the compressor and drain the oil. I would then put in the R134 oil, can't remember what it is called. I think I put about 2.5 ounces in the compressor. You then need to put a new receiver/dryer on. Put the R134 fittings on the line. Pull a vacuum for about 45 minutes and then charge with R134.

If the system currently does not have any pressure then I would pull a vacuum and see if it will keep the vacuum for a couple of hours. If it does not then I would replace the O-rings at the compressor and condensor and retry. If it still does not hold a vacuum then you have a leak somewhere. If the system holds a vacuum then do the procedure above.

If the system does not hold a vacuum after changing the O-rings then you can test the Condensor by using an old expansion valve. Remove the 2 hoses that attach to the condensor and attach the hoses to the two fittings on an old expansion valve. This will take the condensor out of the circuit and you can see if it will now hold a vacuum. If it does then you have a leak in the condensor. This was the test I did and found the condensor was bad and had to order a new one.

I'm not an expert but I have spent a lot of time working on the AC of the several Porsche's I have owned. If you can do it your self it is a lot cheaper.

Good luck

[Razorback1980]

You definitely seem to have a better handle on it than I do. Okay, so let me make sure I have this right. What I need to buy right now is new orings, fittings for the lines and dryer. Flush the system to remove the old oil and vacuum the system. Put the new oil in the system and add freon if the vacuum test holds. I'll give it a try and let you know.

Thanks

[AaronM]

Originally posted by CPorsche
You do not have to change the expansion valve when you convert to R134. I have an 86 that I converted to 134 and kept the old expansion valve, the stock compressor, stock evaporator, stock hoses. I mentioned in the above post that I did replace the condensor because mine had hole in it. I bought the Kuehl super condensor at Griffiths. It cools great, I have to add R134 about once a year. If the Nippondenzo compressor goes bad I will probably replace it with the Kuehl or Sanden compressor. I will also change the hose going from the condensor to the compressor. I believe this is the hose the guy at Griffiths said would leak more R134 because of its design.

If the AC system currently has pressure then I would remove the compressor and drain the oil. I would then put in the R134 oil, can't remember what it is called. I think I put about 2.5 ounces in the compressor. You then need to put a new receiver/dryer on. Put the R134 fittings on the line. Pull a vacuum for about 45 minutes and then charge with R134.

If the system currently does not have any pressure then I would pull a vacuum and see if it will keep the vacuum for a couple of hours. If it does not then I would replace the O-rings at the compressor and condensor and retry. If it still does not hold a vacuum then you have a leak somewhere. If the system holds a vacuum then do the procedure above.

If the system does not hold a vacuum after changing the O-rings then you can test the Condensor by using an old expansion valve. Remove the 2 hoses that attach to the condensor and attach the hoses to the two fittings on an old expansion valve. This will take the condensor out of the circuit and you can see if it will now hold a vacuum. If it does then you have a leak in the condensor. This was the test I did and found the condensor was bad and had to order a new one.

I'm not an expert but I have spent a lot of time working on the AC of the several Porsche's I have owned. If you can do it your self it is a lot cheaper.

Good luck

Ummm... Add the oil AFTER pulling the vacuum, otherwise you'll suck all the oil out too...

Aaron

[Razorback1980]

Got it, thanks Aaron.

[CPorsche]

The purpose of the vacuum is to remove moisture. If you want to remove the oil in the system you need to flush the system.

A high vacuum pump is capable of removing all moisture from a hermetic system by reducing internal system pressures to the boiling point of water at normal temperatures. For those being introduced here to high vacuum work, it should be stated that a vacuum pump does not "suck out" the liquid moisture, but rather causes it to boil in to a vapor state which can be harmlessly removed from the system and exhausted through the vacuum pump.

[AaronM]

Originally posted by CPorsche
The purpose of the vacuum is to remove moisture. If you want to remove the oil in the system you need to flush the system.

A high vacuum pump is capable of removing all moisture from a hermetic system by reducing internal system pressures to the boiling point of water at normal temperatures. For those being introduced here to high vacuum work, it should be stated that a vacuum pump does not "suck out" the liquid moisture, but rather causes it to boil in to a vapor state which can be harmlessly removed from the system and exhausted through the vacuum pump.

I know that's the purpose, but it _will_ remove some of the oil too and you definitely don't want to accidentally end up with too little oil in there. The oil is designed to dissolve into the refrigerant and will at least partially mix with any moisture in the system as well. It just seems silly to guage the oil charge level before pulling the vacuum. Best to pull the vacuum and _then_ make sure that the oil level is correct.

[CPorsche]

Pulling a vacuum is not going to remove enough oil to make a difference, I can't say that it won't remove any, but it would be an insignicant amount. Oil boils at a much higher temp than water and will not be pulled out along with air and water during vacuuming. The point in vacuumming is to remove air and boil off water. You would have to have a hell of a vacuum to even start to boil oil.
You need to add oil to if you have flushed the system. I add oil by pouring the required amount into the lines before closing the system and doing a vacuum. You can also install the oil as you charge the system.
The way to flush the system is to remove the expansion valve and put a flush through the evaporator. Remove the dryer and then run the flush through the lines. You would also need to flush condensor. Flushing the system is a major job but would certainly be the best way to go.

[griffithstech]

Has anyone ever converted to the new 134 by buying one of those conversion kits that include new compressors?
You don't "have to" change your compressor to convert to R134a. What you need to do is first find and fix the leaks.
If there are leaks and you can fix them then you would replace your drier, remove the compressor, dump out any old oil, if you have the tools to liquid flush or can afford to have it done you might want to consider flushing the lines, condenser and evaporator coil, however it is not always necessary, then you would add approx 6-8 oz of ester type ac oil to the system (either before or after evacuation), charge, test, inspect for leaks. (It is not normal for all the oil to be pulled out during evacuation, usually just what is on the gravity down slope. If the ac tech doing the job has the correct equipment they can see how much oil was removed if any and replace it after evacuation.... good questions to ask the ac tech to qualify him or her... to politically correct).


Are some (compressors) better than others or are there differences in some.
The OEM compressor is a Nippondenso 10p15 (base unit) "swash plate" compressor. You can get away with a Sanden "wobble" plate or go back to equal to OEM with a Kuehl trademark "swash plate".


I have seen some conversion kits including new compressors and was wondering if those make any sense.
You would consider replacing the compressor if it is not pumping correctly, it is noisey, it leaks, or has damaged mounting ears. I would avoid attempting to repair the unit if it has over 100k miles on it, unless you have experience in inspecting for piston, cylinder or plate wear... here is where you would consider a complete "kit" perse that has a compressor and R134a conversion components (such as drier, adapters, etc).


In Houston, a/c runs all year around or real close to it. It's actually 80 degrees here today and this is our coldest month of the year.
80F ? hmmmm, not a bad time to do some other inspections on the car.


Mine isn't actually really broken, but it leaks and has to be filled often, so maybe I should put on a new compressor and upgrade to the new freon.
Consider the mileage on the compressor, weigh the option to try to replace the seals vs. time and materials and the cost in the refrigerant procedure, and think about it for awhile. 80F is perfect weather compared to 20F here.

[Eldorado]

my buddy has used R12 replacements such as DuraCool for a few years with no ill affects.... might be the route i go. and you dont need to replace anything in your system (provided there aren't any leaks)