[Cloud9...68]

When I drove my car today for the first time in nearly four weeks (been recovering from surgery on my right shoulder), the A/C was running fine, until about 15 miles into the drive, when it pretty suddenly went from blowing nice, cold air, to air that was getting cooled only slightly below ambient temperature. It's still being cooled enough to making the car more comfortable to drive with the A/C on and the windows closed versus rolling down the windows, but just barely. There was no noise when the problem started, and the belt is fine. The fan blows at normal velocity, it's just that the air is no longer cold. The previous owner replaced the A/C controller unit about 3-1/2 years ago, and I replaced the AC compressor clutch about 3 years ago, not that either of these mean a whole lot.



I tried doing a search, but the search function wouldn't accept "AC" or A/C" because they are less than four characters, and "Air conditioning" didn't turn up anything useful. I haven't followed A/C threads; is there something in the A/C systems of these cars that's a relatively common source of trouble that I can troubleshoot myself? The fact that it went from normal to bad so suddenly suggests something other than a freon leak. Thanks.

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[gryphon]

I believe that when the refrigerant charge drops to a specific point the compressor will no longer work. You should be able to hear and feel the compressor kick on/off in your garage.



Tom

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[Cloud9...68]

[quote name='gryphon' post='40098' date='Aug 18 2007, 04:53 PM']I believe that when the refrigerant charge drops to a specific point the compressor will no longer work. You should be able to hear and feel the compressor kick on/off in your garage.



Tom[/quote]

Except that it's still cooling to some degree, maybe 20% of normal. While the drop in cooling ability was fairly sudden, it didn't completely go away, which is what I would have expected if the compressor had stopped working altogether, right?

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[sasilverbullet]

It's low on freon, charge it up and all will be good...

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[PorscheDude]

Do the cooling fans come on when the A/C button is pushed? You could have blown the fuse for the fans or the relay could be on its way out.

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[RPM]

If it is still blowing a little cool the best guess is low freon. However, freon does not get consumed in normal operation. Low freon is often the sign of a leak. Unless you are experienced and have the correct hoses, fittings,a nd guages I suggest you have the recharge done by a pro who can also test the system for leaks when they recharge it.



Texas summers are too hot to be dorking around with this for days.

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[sasilverbullet]

I have/had a tiny leak in one of the fittings to the condenser up front, takes two years to leak out enough freon for the thing to quit.



I bought a can of freon with the stop leak stuff in it and since then haven't needed to refill it.

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[Cloud9...68]

Thanks, everyone. The consensus seems to be low freon, contrary to my initial impression, probably due to a leak. To answer smokiemon's question, no, the cooling fans don't come on when I press the A/C button. Given that the (coolest by far I've experienced in the 16 years I've lived in Texas) summer is winding down, I think I'll first try sasilverbullet's method, and if that doesn't do the trick, I'll take it to someone equipped to work on A/C systems.

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[sasilverbullet]

And if you want, you can drive your car down and we'll use my neighbors lift and charge the a/c, and maybe have a beer or two... <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

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[Cloud9...68]

I have a neighbor with a 964 who recently recharged his A/C, so it I get into trouble, I should be OK, but depending how things go, but I may just take you up your offer <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" />

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[moses]

I recently recharged mine and it went ok but in retrospect I wish I had taken it to a shop. The low pressure port on the compressor was corroded (how can these not be stainless!?) and I had to work it quite a while with steel wool and a wire wheel before the fitting from the 134a can popped on without leaking (much). In the process I lost some freon gas and about a tablespoon of oil. I wish now I had taken it out, had it drained, the fitting replaced, and refilled with the correct amount of oil and freon, maybe one of the hydrocarbon substitutes, Dave Greimann had this good post about them:

http://www.968forums.com/index.php?showtop...05&hl=freon

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[andym968]

For what it is worth in a recent post of mine I mentioned that I just bought my first 968 and the AC was not working either.It cooled only very slightly as you indicated.

Porsche drained and refilled the AC unit and now it works perfectly, in fact it is some of the coldest air I have ever had out of any AC unit...so hopefully for you this should solve your issue as well.



regards

andy

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[Richard]

Cloud: Has your 1992 been converted to R134A? If not, it has R12 and should be done at a shop. They can also put in some dye to track down the leak.

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[Cloud9...68]

[quote name='Richard' post='40218' date='Aug 21 2007, 04:24 PM']Cloud: Has your 1992 been converted to R134A? If not, it has R12 and should be done at a shop. They can also put in some dye to track down the leak.[/quote]



I think my AC has been converted to R134A, but I'm not sure. Any idea how to tell? Thanks.

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[sasilverbullet]

the new freon's fittings are almost 1/2 inch in diameter, the older ones about a 1/4 inch...

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[Cloud9...68]

I checked the fitting (it's the capped thing directly in front of, and just slightly below, the overflow tank, right), and it's about 1/2", so I guess my car got the R134A conversion. That's great, as it will make refilling MUCH easier. Thanks for the tip.

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[Ryan]

The R12 is a schrader valve (think tire valve stem) and the 134 valve is a quick release bannette type.

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[Richard]

By law a shop that has done an R12 to R134A conversion has to put a sticker in the engine bay (usually on the inside of the hood) stating that the conversion was done. It should have the date when it was done. They are required to put on R134A conversion fittings as well.

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[Cloud9...68]

[quote name='Ryan' post='40316' date='Aug 23 2007, 04:40 PM']The R12 is a schrader valve (think tire valve stem) and the 134 valve is a quick release bannette type.[/quote]

Mine's definitely the latter. I'll try to charge it up this weekend. Thanks for all the advice.

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[Cloud9...68]

OK, what I thought was the correct fitting is actually the high pressure side. Summer has finally arrived here in Austin, so it's very uncomfortable in my garage, so to save me a little time hunting the thing down, where exactly is the low pressure fitting where I need to fill the R134? I didn't see it on thetop side, and sasilverbullet mentioned putting the car on a lift, so I imagine it's underneath. Thanks.

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