[jlgryder]

I was hoping someone could help me with my air cond problem. I am currently a 944s owner but plan to buy a 968 cab this summer. In the meantime I need air. I had my system evacuated and then put the retro valves on. I am converting R12 to 134a. Anyway, the psi should be at about 25 to 45psi when full. I put in about a 1/2 can and it is at 100psi already. I am not sure why it wont allow me to put any coolant in the system. Any ideas.



Thank you,



Jason

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[Greimann]

It sounds like you are on the high pressure port, when you should be on the low pressure side. The low pressure port on a 968 is on the bottom of the compressor. You have to crawl under the car to get to it. Not sure if the 944 is the same.

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[rustech]

I also think you are charging it on the high pressure port. That's a sure way to blow a fitting or even the can of 134. To charge the system, make sure the car is running with the A/C to max.

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[jlgryder]

Thanks guys, I think you are right. The kit that I purchased said that you can't go wrong because only one fitting fits the can. It also states that there is an optional fitting for some late model European cars. I will get under the car tomorrow and see what I come up with.

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[flash]

it was my understanding that some seal or other major components or something also had to be changed to do the conversion - is that not right? it was a pretty pricey job on gene's car

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[jlgryder]

I have spoken to three seperate mechanics. One is a Porsche mechanic and the other two are just general... All of them said that in the past it was recommended to change out your pump but nobody does this anymore. It was something to do with the oil left over by the R12. The only recommendation now is to remove the oil and replace it with 132a compatible oil, and of course change the fittings. And this isn't even necessary but if you don't do it you won't get the full potential from the new coolant. Ask around, but I haven't heard anything different from this.

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[Greimann]

If Genes conversion was pricey, he may have a had leak that needed to be fixed before they charged the system. Sometimes on older cars, there are some o-rings that needed to be changed to another material.



I would say that changing the receiver / drier would be a wise move. R134 need to be moisture free and a new drier would not hurt.



Purging the old oil is very important. The new oils and the old are incompatible and will form a sludge that will kill the compressor.



And then of course there is the hydrocarbon option......

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[schwarz968]

About 11 years ago I had a late 85 944 which I purchased with a bad A/C system in it. I thought the guy was nuts to sell the car so cheap ($7K) <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" /> but once I saw just how bad the A/C was going to be, I see he cut me a deal. <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" />



I had tried going to a different compressor (Rotary) originally to save $ and had to cut the ends off the original lines to install adapters for the new compressor. Mistake!!! <img src="/forum/images/smilies/968/mad.gif" class="smilie" alt="" /> The compressor was garbage and the system never ran well.



I put the old compressor back on after rebuilding it , spliced the compressor connections back on to the lines but had too many leaks. As an old aircraft mechanic I can say they weren't from my splices but rather from 4 or 5 O rings throughout the system, as well as behind the clutch at the compressor split line. As a result of all the wasted time and money not to mention really wanting a system FREE of problems, I did a complete rebuild of the system.



I worked with with Wayne (Svc Mngr) at Jim Ellis Porsche (yes he is still there) 10 Years back and I installed a retrofit kit from Porsche. I had to change out the hoses, compressor, Expansion Valve, Receiver drier, Compressor and flush everything out. The new lines had the High/Low connections in the same place as the R-12 and we installed the R134A adapters and the two new decals in the engine bay. The system worked extremely well and I did all work except for the flush, evac and actual charge of R-134a.



FYI - Porsche says you need to pull the center console/dash to replace the Expansion valve and will charge you two days labor. I went in through the engine compartment, pulled the blower motor/fan assembly and whala...there it is, straight down. I hope this info will help someone.



Stephen

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[Greimann]

[quote name='schwarz968' date='May 24 2005, 05:49 PM']FYI - Porsche says you need to pull the center console/dash to replace the Expansion valve and will charge you two days labor.  I went in through the engine compartment, pulled the blower motor/fan assembly and whala...there it is, straight down.    I hope this info will help someone.

[right][post="5034"]<{POST_SNAPBACK}>[/post][/right][/quote]



Nice! That is great tip! I had bought a new expansion valve for my system and when I found out about where it was, it went into the spare parts drawer! This isn't such a bad job now!

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