tgfarns

What should I expect to pay for this and can I go to any shop to have the work performed? I would rather not pay the $80/hr to have a porsche specialist work on this, if possible...

Thanks - tgf

jebia

I just paid $240 in Albuqueque (Dan's Automotive) , it works great. Nice and cool in 97 deg weather yesterday.

Bret 944

WOW! That seems really expensive ! Maybe cause summer just started ? I bet its cheaper to get done in the winter...

Yabo

was this to flush, convert (parts included) and refill?

jebia

I think they call it an evacuation (of the old refrigerent), at the same time they check the system for leaks, perform any repairs etc (my system had no leaks). They they install new inlet fittings (new refrigerant style), and fill the system with the newer style refrigerent. I think they said my system uses less lbs of the new stuff than the old stuff to do the same amount of cooling.

jebia

Besides the fittings, no other parts were replaced (everything was in good working order before, my system was cooling, but not at peak efficienty because I was a lb or so low on old style refrigerent). It's getting so hard (need a certificate and its costs a lot per lb) to get the old stuff, I just decided to pay a bit more and have the system updated.

Yabo

I thought you needed a new dryer and maybe some other things to update? 240 sounds like a deal to me to get my system going..

Porsche-O-Phile

Hah! You guys are spoiled! Same service out here is over $400.

Tony K

And now, for a mere $25, you can buy a cheap gauge and just check the high pressure side once a year, and if it is low on pressure, just buy a can for $7 and put it in yourself. They should have noted on a sticker whether they used esther oil or PAG oil.

Tony K

Here is something to keep in mind: You can buy a halfway decent vacuum pump for $300 with fittings and hose. Halfway decent gauges can be found for under $100. The adaptors are a few dollars, as are r134a and compressor oil. For pretty much the same price, you can do it yourself, keep the equipment, and take care of your family's and friends' cars, too.

Tony K

Here is a logic problem:

Back in 1996, my air conditioning wasn't working. I had a few cars, and it worked on none of them.

All of the "reliable" and "informed" and "official" sources told me that to convert a car to 134a, I needed to spend over $1000 on "barrier hoses", dryer, compressor, fittings, and on some cars a condenser.

I asked "What will happen if I just try to put the new refrigerant in the old system?", and got answers such as "NOOOO!!! DON'T DO THAT!!!" and "That is harmful to the compressor" and "it will all leak out" and "you will ruin the AC system in your car" and every horror story imaginable.

R12 was $30/lb. at that time (I hear it's more now). That stuff has to be the most regulated substance in this country next to uranium. I wasn't allowed to buy it, I wasn't allowed to use it, own it, touch it, nothing. I could only pay someone to put it in my car, and pay all kinds of fees along with it. I could pay a couple hundred dollars to get certified myself, but the fees and extra work associated with buying and handling R12 made the whole thing seem not worth the money and a waste of time.

So, my choices were to spend several hundred dollars to pay someone to charge my AC system, who would inevitably try to replace every O-ring along the way and bilk me for every penny; to spend several hundred dollars to certify myself and go through all that hassle; or spend a few hundred dollars more to have my car "properly" converted to R134a.

But, as it was put to me, if I wanted working AC, there was no way out of spending several hundred dollars minimum, if not over $1000.

So, going back to my original question of "What happens if I put 134a in my car?" The conclusion I came to was "What do I have to lose?"

I vacuum pumped the system as a precaution against what I had been told that "If the mineral and esther oils mix, they will break down and lock up your compressor". So, vacuum pump sucked the system bone dry and also verified no leaks.

In went the R134a. What would happen???? I almost wondered....

And, of course, what I ended up with was ICE COLD AC. No changing compressor, no changing dryer, no changing condensor, nothing. Refrigerant out and refrigerant in. That's it. Done...

"Oh, but the refrigerant will leak out of the old style hoses, they are not BARRIER HOSES!" . . . . .. yeah, really? Five years and about 50k miles later, the AC still worked fine. Never needed to be topped off. When you think about it, it is not uncommon for five year old (from NEW) cars to develop leaks in their air conditioning. Maybe there is truth to the whole "barrier hose" thing, but in reality, an O-ring or something will go bad before any refrigerant seeps out of any microscopic pores in hoses.... Which I still think is a total load of B.S. . . .

The nice 944 you see in my Avatar had a system that was low on R12 when I bought it - low enough that there was not enough pressure for the compressor to run. So out went the R12 and in went the R134a. ICE COLD. Much colder than my previous car that had the supposedly more efficient compressor from vertex. 20k+ miles later, everything is still fine. Looks like you don't need to do anyting to 944s.


As for the dryer, think of it in terms of a can of silica gel. If it gets exposed to humidity for a long time, it will absorb moisture, and you want it dry when you put it in the car. If it is exposed for a long time, it won't work as well. Or so I have been told. . . . (by the same people who warned of armageddon if I put R134a in an R12 system). Given this, I wonder if I can "recondition" a dryer by putting it in the oven for several hours...? Either way, the dryer on your car will be fine if it is disconnected for only a short time.

Cheers,

Tony

Yabo

Thanks a lot for that information tony. So could a shop vac or something suck out whatevers in teh system now? and what about the oil or whatever in teh compressor do you have to renew that somehow?

Sorry, I just never really understood how this whole AC system , or any for that matter, is set up.

buckshot

last summer, my conversion cost me (including a trip to a state certified recovery center)
approx $400.00 this incuded new dryer, fill with proper oil, and fittings.
wisconsin is really fussy about freon discharge in the air!!
have fun, keep cool, (mine is still very cool)
buckshot wi

Tony K

A vacuum pump is about the size of a ladies' shoe box and has a hose with a fitting that screws to your car's schrader valve or R134 fitting just like if you were attaching the gauges to it. It is a tight, high pressure connection, not like a bicycle pump. You can buy them at tool supply places, and there are some models in the $250-$350 range that will work. One popular brand is Robinair. If you know anyone who works in HVAC, whether for buildings, appliances, cars, or whatever, he will have one.

To use it, you connect it and turn it on, and it sucks everything out of the system. It has a gauge on it that measures the level of vacuum. I believe it should read... 29" of Hg? (someone who does it regularly can verify this). Vacuum is measured in "inches of mercury". If it does not get to that reading, then you have a leak in the system. If it holds the vacuum, leave it running for a while longer to make sure every last bit of everything is out - maybe not necessary, but doesn't hurt.

Then, shut it off, and leave it connected so it maintains the vacuum reading. If the in/Hg drops slowly, then you have a slow leak. If you can leave it connected over night, all the better just to be sure. Why not.

At this point, your system should be bone dry inside. On my 85.5, I decided to take the compressor out just to be sure all of the old oil was out, because someone told me to. When I disconnected one of the lines, there was a loud pop from the vacuum in the system being relieved, and what I found was that everything was indeed bone dry. Next time I won't bother, as I never bothered to on my previous cars.

But to answer your question, no a shop vac is utterly useless here. A vacuum pump is pretty much it. There are cheap $20 attachments you can attach to an air compressor that will suck your system, but I don't know if they work or are total throwaway junk or what, and you will have to buy a separate vacuum gauge then.



Regarding the OIL,

The story is that R12 uses a mineral-based oil and R134a uses an esther-based oil, and catastrophe will happen if they mix. Hence the need to vacuum the system.

Now that your system is bone-dry inside, you have to fill it with both refrigerant and oil. I forget what the ratio is, but it is somewhere in the ballpark of add 1 oz. of oil for every 3 oz. of refrigerant. But I don't know this - this is just a guess and I may be way off, so look it up, or maybe someone else will chime in. Somehow that seems like a lot to me, but IIRC, when I filled my system I started with around 8 oz. oil and 24 oz. refrigerant and it has been working fine, but what do I know...

The refrigerant and oil should be added to the low-pressure side of the system. This is NOT the one by the receiver/dryer (by the headlight). On 944s, the low-pressure valve is usually near the left fender near the air box, or by the compressor on the early cars, IIRC.

IIRC, the pressure on the high side on a properly working system should be somewhere around 270-300 lbs/sq.in on an 80 degree day at a sustained 3000 rpm, but don't quote me. I do know that my vents get the coldest and the compressor cycles off right when it hits 300 under these conditions. It works. Cold Air. That is all I know - I'm just a backyard, backstreet, streetlight, parking-lot mechanic. . .

To be honest, I have no clue what the ratio of refrigerant to oil should be, but it is more approximate than precise. I should probably look it up and "guestimate" what I have in my system and correct as necessary . . .

But hey, what do I know. This is just my poor man's experience with having Ice Cold Air... Get some real advice from someone who knows!



Tony

Yabo

I've never seen so many disclaimers in one post, ever.

Well it seems that the cost of the pump pretty much negates any cost saved by doing it myself... Unless somewhere will flush the system for me for cheap.

Anyway, thanks for the help.