Mike Hubert

Quick question on my 91 C4 Cab. The AC has never been super cold (had the car for two summers). What is the take by the experts in this group (and as a newbie I have learned more in two days on this site, than the past two years with the car) on this. According to my service techs everything looks good. Also, what is your take on upgrading(???) to the new coolent type? Some tell me to do it (obvious cost advantage) others say the system will never be the same.

Any thoughts would be great.

Thanks,

Mike

Bill Wagner

An AC expert I'm not, but I'll throw in some opinions anyway.

My car is a '91 C4 w/22K on it. The AC was recharged in the winter during a major service. It isn't the coolest AC on Earth, but it isn't the worst either. An old '87 RX-7 I had (with the old freon) could not cool as well as the C4 does. I have a '96 Nissan 300ZX as a commuter car, and it doesn't cool as well. The 300ZX uses the "new" freon, and it appears the way Nissan did this was simply take a system designed for the old freon, modify it slightly, and then install the "new" freon. The change, in my opinion, was marginally successful. I've been in older 300ZXs that use the older freon and (if they're working properly) they blow cold air out like a freezer. The "upgraded" AC system in my 300ZX is no where near as good.

You need to compare apples with apples and in this case, and I guess my 300ZX comparison is about as good as I can do for you. For what it's worth, Porsche does not recommend the "upgrade", at least the last I heard that was the case. The fact is that unless we want to start recharging our systems at $500.00 or $1000.00 a pop, upgrades and replacements are probably not only worth looking into, but will eventually become neccesary. In the case of 964s, I think this will likely mean a complete replacement of the system with one that is effective with the new freon. Some may already be available, but I haven't looked into it yet because there's no need on my part to do so.

Hope this helps,

Bill Wagner

Adrian

Dear Mike,
Keep the roof down and enjoy the sun. The Porsche airconditioning system in standard form just never works properly. Some people have invested in upgrades. A full upgrade in the USA, new compressor, basically, new everything is around $US2,500.
Here in Europe it is almost impossible to find a 964 Cab with airconditioning anyway.
Of course the aircon cannot cool the world and the Cab is not the most airtight in the world either. However, the 964 airconditioning whilst an improvement on the pervious models is still way short of the mark. Engine at the rear and condenser mixer and evaporator at the front make for a vapour cycle design that really can never work efficiently. I actually recommend you remove the system in a Cab and save yourself a lot of hassle, less parts to fail and of course around 40lbs in weight.
Ciao,
Adrian
911C4

Riccardo

Adrian,

If I'm not wrong I believe that during its production lifespan the 964 had two different types of refrigenrant used. Initially it was the R12 but later they changed to R134a.

Is this correct? If so, when was the change valid from?

Thanks

AdamKWeinstein

Mike,

My 93 RS America has been converted to R134a and runs very cold. I live in south Florida and have no issues with my a/c cooling during the summer. The only problem, in my opinion, is that the 911 does not have a large enough blower to move the cold air around in the cabin.

The cost of a conversion runs about $300 in parts (new expansion valve, drier, and update kit with new fittings and o rings for compressor). The compressor and lines do not need to be changed. However, as 911 systems are prone to leak over time, once per year I recharge the system (you will need to purchase a $30 gauge) with two cans of R134a ($5 each).

This conversion is simple and can be done by a shadetree mechanic or by any reputable a/c or Porsche shop.

Best of luck, Adam.

Randall G.

The A/C in my 964 has always worked, and has only been recharged twice in 9 years. On a day when it's not too hot or the sun isn't shining too strongly, it's cold enough to make the wife beg for mercy. On really hot days--or when the sun is especially strong (my windows are not tinted), it's adequate.

Car & Driver did a long-term test on a '95 993. One of their biggest gripes was the A/C being barely adequate (or something to that effect) on 104 degree days.

Anyway, while the 964 and 993 do have much improved HVAC as compared to previous 911s, the A/C still isn't as good as the A/C in a low-budget Japanese car.

Drew_K

The A/C in my 92 C2 coupe works well unless it's over 90 degrees AND it's been sitting in the sun for a period of time. However, compared to my wife's new Camry, my A/C is pretty decent but no where near the capability of the Camry.

Looking over my maintenance records from the previous owner, the A/C was recharged about every 2 years, and it's been about 2 years since the last recharge. Mine's been working fine this summer, but I may have it recharged next spring just in case.

Randall G.

Drew's exactly right ... I forgot to mention that my A/C struggles to recover from a pre-heated interior. Doesn't help any having a black interior.

Roland Kunz

Hello

The 964 AC is designed to use R 134a. However they made it not in time to be faster the chrysler and all 1993 MY came with the new coolant.

In the last years the factory offered a collant swap for 150 $ inclusive waranty.

Had seen the action "Klimawechsel" flyer is still around at the factory and so they still offer it maybe not for that price anymore ( Some 3 years back ).

However R12 is totaly baned in germany and so there is no alternative exept one drop in with is not recomended by any car manufactorer ( maybe to make more money ).

In issue for low performance is the failing condensor blower resistor. This has been covered before and can be found in the archives. ( maybe 993 )

Grüsse