Gregs04.5

Has anyone converted their 944 to R134? I did a search for r134, and did not find much here.
Looking for what needs to be changed, upgraded to make it work.
Mine has leaked out all the r12, zero pressure, so I'm going to have to track down the leak and reseal the system.
Thanks in advance, Greg.

pdxfj

Google "Porsche 944 134a conversion".

All kinds of threads show up here.

R12 is not that expensive. I was quoted about $40/lb at a local shop. Even with my leaking system, last summer I was able to achieve 40 degree vent temps on a 90+ degree day with R12. In the middle of completely redoing my A/C and will stick with R12. New hoses, compressor, o-rings, etc.

djantlive

I changed to r134 w decent results. It worked for 4 years on the original compressor. Then, I had to put in a new denso compressor and receiver when the original one gave out. Works well again.

So, no problem with r134 here.

951Dreams

I'm no HVAC guy, but two things to consider. I've been told R12 works better, and that 134A is much, much, much more prone to leaks.

For me, the only pressing reason to switch is if your replacing everything anyways. I don't know if it applies to our cars, but I've heard that some R12 systems won't hold the much smaller molecules of 134A correctly, no matter what you do. Something in the design. 134A can find routes to escape. Don't know how true that is.

My 87 has a 134A sticker on it, but there is no conversion in the history. The one work order I've found about AC shows both R12 and 134A charges, I have no idea what that's about. I've looked at the fill coupling, but upside down in the dark I could never decide which it was. And some times they convert it with an adaptor, so that wouldn't​ mean much anyway. I'm not exactly sure what I'm going to do once it needs refilled.

The 86 I'm getting has recently had a 134A conversion. The main advantage of converting is you can go to Walmart and get 134A. It can be a challenge to get R12.

I've also read conflicting opinions on mixing the two. From you'll blow up this sector of the universe, to everything works fine. (The blowing up thing was tongue in cheek.... I think... it's hard to tell)

I just went and researched this again. It's worth looking into other things than R12 and R134A as well. But no idea how these 944s handle alternatives.

Ish_944

I had mine converted 2 months ago. It's still too cold to tell, but the AC guy measured 2 Celsius blown in his shop which was probably at 18-20 Celsius. He was surprised that it worked this well.

I needed a new condenser cause the old one had holes. A few hoses were also rusty, new drier, o-rings and I guess that was it. Oh, my compressor had to be rebuilt, too.

Van

A few things to remember:
-Make sure the new oil you use the R134a is compatible with the old oil from the R12 system
-Consider getting a new condenser (the "multi-row" style is more efficient for R134a than the old "tube" style)
-Remember that the charge amounts are different
-Replacing all of the o-rings in the system will help prevent against leaks

KevinGross

Van's advice is correct. You will need to replace all the o-ring seals with ones that are compatible with R134a, replace the dryer, and fill the system with the appropriate amount of R134a compatible lubricant. There's nothing special or unique about the 944 AC, you can work from generic conversion information.

However, unless you want to invest in the tools (mostly a vacuum pump, manifold gauge set, can tap), it will be cheaper to have a shop do the conversion for you. You will not get good results from a quicky top-off kit.

Jfrahm

I am experimenting with R152A for better performance and compatibility with good ol' mineral oil. I was running it last year and very happy but over the winter I have discovered that I have a bad Schrader valve (brand new one from a santech kit) that I am now going to replace them both with the highest quality valves I can find and recharge with another $6 worth of R152A.
I have converted one of the spray caps from the R152A can to fit a charge hose so I can use the product without piercing the can and thus can keep a half a can around for months and months easily also.

There are vids on youtube about this conversion as well as other threads here.

-Joel.

pfarah7

I changed mine over to 134A four years ago; replaced the high pressure switch and dryer but kept the original compressor. It worked for a season then the compressor died a horrible death.

The following spring (2014), I purchased a rebuild Bosch Compressor and replaced all O-rings, high pressure switch (again), dryer (again) and the expansion valve. After rebuilding the system, I had the AC evac'd and filled twice. She's been perfect ever since! Anyone that thinks the 134A doesn't blow cold is invited to sit in my car and become tantalisingly chilly. Even during the nasty month of August, I rarely turn the AC fan on high or keep it on that setting for more than a few minutes at a time. Just my thoughts...

Van

Typical when the oils aren't compatible.

Roka

How do you account for the r12 lubricant already in the system? assuming the r12 leaked out of the system years ago, is there any substantial amount of oil still left that needs to be evacuated.

Otto Mechanic

Not sure if this would work, but I re-built the Denso compressor in my 85 928 a couple years ago with a $15 seal kit from an outfit in AZ and a $25 special tool for taking the clutch off I got used from eBay.

It was a lot cheaper than buying a rebuilt compressor and it only took about a half hour. I didn't convert mine though, just took it out, re-sealed it and filled it with R12. Not sure what sort of damage mixing the oils can do, I ended up using an oil that was supposed to be compatible with both.

MistaX

To fit R134A fittings on an early compressor requires a shorter than factory serpentine belt due to the location of the high side fitting. An adapter fitting is just too big to fit between the alternator and the A/C compressor at proper tension, and the A/C can't be charged without the compressor running. Tried a couple fittings when I did it. Straight, 90 degree, etc. There's just no room for any of them that I could find.

A shorter belt brings the compressor closer to the engine fully tensioned and leaves enough room between the compressor and the alternator to fit the adapter, and it can be left there for future maintenance.

Assuming this is for the car you list in your sig, an '84, this is very relevant.

pfarah7

Actually, the original compressor just gave out. I had the original system evac'd for over 45 minutes so I don't thinks there was much of anything left in there.

V2Rocket

simple answer for R134 conversion:
-- replace all the O-rings in the system
-- drain compressor of as much oil as you can, find new oil that is compatible with R12 and R134 (name escapes me currently)
-- remove condenser from the car and backflush with mineral spirits or other suitable solvent and compressed air to push **** out and dry the inside...let it sit in the sun for a while to warm up and let any residual MS out
-- comb fins of condenser clean of birds and rocks and leaves and make them straight again - this will make a huge difference in efficiency
-- remove the high/low side R12 scrader valves and fit the new R134 adapter fittings with new valves
---- if you have an early car you need to get a 90-degree adapter fitting for the low side that mounts on the compressor, to clear the alternator bracket
-- pull a vacuum as far down as you can on the system to check for leaks - i have a monster pump that goes to -30 inches. leave it under vacuum for a few hours and occasionally check the gauge reading to make sure it isn't leaking
-- when you go to fill the system, leave it under vacuum. start the car and let it run, hook up your r134 can to your gauge set and shake the can a bit, open the valve and the vacuum in the system will help to draw in the first bit of freon. activate the AC switch and fan to max and just shake the hell out of the r134 can to get the gas flowing, eventually the compressor clutch will activate and begin pulling freon from the can on its own.
-- R134 fill capacity is about 75-80% of the R12 amount written on the sticker on your fender.
-- TYPICAL fill pressure i have seen on 944 (with the compressor running) is 30-40psi low side, 140-150psi high side. depending on ambient temperature and your individual system it may vary a good bit.

i have done my own car "a few times" over the years for various reasons and a few other 944s as well.


i'm sure our dear friend griffiths will come along to this thread soon and add his excellent input from years of experience doing Porsche AC.