Porsche Air-Con/CC systems are very poor.

Previous poster said:

Quote: Originally posted by Hendo on 01 July 2005

Can only say that the 996 Air con is as cold as a polar bears bum when you need it. Admittedly a more recent car but I think they put some effort in this time

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Agreed. I don't have the 996 yet (getting one inspected this morning), but before my test drive the car had been sitting in the sun all day. After a couple of minutes with the engine and AC running it was like slipping into a cool spring morning.


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The 996 was very much designed around all of its requirements whereas in previous versions of the 911 space had to be found for modern features such as airbags, climate control systems, intercoolers, etc. This allowed Porsche to ensure the requirements weren't compromised too much during their implmentation, hence such things as very effective climate control systms (with an AC condenser in each front wheel well) and turbo cars having intercoolers in the rear wings instead of in a coffee table sitting atop the engine lid.

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I must admit, if there's one aspect of the 993 I'm not so keen on it's the ventilation. I usually seem to arrive at most destinations all hot and bothered! :evil:

Plus have you noticed how the sunroof just sucks in all the heat from the engine, and you just get even hotter?

Incidentally, my aircon's packed in completely now, so I must have had a leak....


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I think my C2S aircon is pretty good, though with a smallish cabin the car heats up quickly if stopped (i.e. engine off) and under a blazing sun, which then takes a while to clear unless you open the windows for a while to help it a bit.

It works best at cooling the cabin with both sliders over to the left. (Sorry if this is obvious, but it took me a while to figure out.

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Turn on ignition - start engine - half a mile later its blowing cold air - no problem - just as fast as the 2005 Audi A3. Coped with 2003 100 degree heat wave in France and italy too. And its a Targa with higher solar gain.

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I found this on Rennlist - might help some people with aircon problems.

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I thought I should post the solution to an A/C problem that I was having with my '97 C2 for some time. Not so much for the fact that anyone else is experiencing this problem now, but for the 'archives' and future reference. This was a tough problem to chase down and something that is really an inherent defect in the 993's A/C system.

First of all my car has about 28,000 miles on it and I've had an A/C system problem since I've owned it the last three years. In the cooling season the A/C would operate normally per the Shop Manual's performance chart. Center vent temps would be 48 F to 52 F depending on ambient temperature, engine speed and settings. Normal (and anemic), but good enough to handle the Upstate NY summer temps. As most of you do, I keep the car in the shade with a window shade in place if it is blistering hot outside, to keep the interior from heat soaking. The initial cool-down is where the A/C system shows how under-sized it is.

My car's A/C problem became evident only under certain conditions. After a 30 to 45 minute drive in extremely hot 85 F + and high humidity days, the A/C center vent temperature would start to climb from the 48 F to 50 F range up to 65 F to 70 F. The center vent temps would level off in this range and not go back down.

After getting the car back home and parking in the garage you could not see any dripping from the evaporator drain - the evaporator had completely iced up solid. About 15 minutes later this ice would begin to melt and the water would run in a stream from the drain area under the car.

Cantech Automotive in Syracuse attacked the usual suspects and did a thorough job of charging and pressure checking the system, checking compressor operation, replacing the evaporator expansion valve, evaporator temperature sensor and dessicant tank. The problem persisted and really made me avoid driving the car in hot and humid weather all together.

Finally, Cantech brought the car back into their shop and ran more tests on the system. Fortunately the weather cooperated with extremely high temps and humidity while the car was at their shop. They checked that the evaporator temp sensor, CCU and compressor were all cycling properly as the evaporator iced up (as it is supposed to do), but that by the time the temp sensor mounted on the evaporator reached the correct temperature and set a signal to the CCU to shut-off the compressor, the evaporator was iced up solid. The problem was that the compressor was continuing to run long after it should have, causing the evaporator to ice up solid. No air flow and hence the high center vent temps.

Cantech felt that the only solution would be to relocate the evaporator temp sensor lower on the evaporator core so that it will see the lower temps (ice-up) sooner, and send a signal to the CCU to shut off the compressor. The evaporator then has an opportunity to melt off the ice, the compressor turns back on and the cooling cycle begins again. Discussing this with Cantech I remembered some posts from several years ago here on Rennlist from guys that had this ice-up problem and used the temp sensor relocation as a fix. I found three or four discussions of this topic using the 'search', and while the discussions were specific as to the fix, they were buried in threads from several years ago.

Cantech relocated the evaporator temperature sensor lower on the evaporator core by about 2" or so and after driving the car I noted that the center vent temps would now fluctuate by 2 or 3 degrees while driving at a steady highway speed - meaning that the A/C compressor was now cycling on and off when commanded to do so by the evaporator temp sensor via the CCU. Since this change was made I have driven the car several times in temps and humidity that would have, in the past, caused an ice-up event and the A/C has worked fine.

Sorry for the length of this post, but I thought a thorough explanation was in order as this is more of an inherent manufacturing issue that an owner may have to deal with, rather than a typical maintenance issue. Hopefully this post may save a future 993 owner a lot of hair pulling and cussing. Thanks to Rocco at Cantech in Syracuse NY and Randall G. (Rennlister) in California for their help.

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Just had my gas changed at jz and now works at least 3x better then before...

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