IXLR8

I finally got out yesterday for my first drive since mid May and it being as hot as it has been, noted that the A/C on MAX just wasn't working as it always has. The A/C was working but very little cold air was making it out the vents.

Hearing a swish-like sound told me that there was some sort of restriction; a vent flap not opening or something like that.

Sure enough, today I had a quick look under the engine lid and found a rubber vacuum line split.

The rubber elbow shaped hose (number 27) where it attaches to the check valve (number 28) was split. According to the parts list, there are 7 of those elbows in the engine compartment. In the hot environment, it might be worth changing all of them.

That took all of five minutes to diagnose...luck was on my side.

Leon993

great job!

I live in New Mexico and we get 95 degree summers, the 993 AC system has lots to be desired. I've always been curious if there have been any after market improvements on the AC design of the 993.

ToreB

Good to see you found out Alex!
The resirculation flap is vacuum operated, and will not (fully) open if there's a leak somewhere. That's why you heard the wheezing sound. At minimum temp setting and hot air outside the fans could not get air from anywhere since the fresh air and hot air flaps are closed.
Details here: www.ccu.tore.bergvill.com
Cheers,
Tore

IXLR8

Well its not that hot here, but it does get into the low 30s ˚C (high 80s - low 90s ˚F) here and my A/C works very well. On MAX A/C, I have to turn it off after a few minutes and switch to regular A/C or I'll freeze.

The temperature differential between my high and low pipes is high; I'll have to measure them with my thermocouple probe.

IXLR8

Tore, is there a line drawing diagram anywhere on the web?

Maybe I'll check those factory Porsche service manuals that I ordered and haven't cracked open yet.

The climate control system seems to be electrical/vacuum operated. I'll dig into it when I have time...I just got back from 6 weeks of motorcycling in the Alps and have a lot to do at the moment.

Zingari

How do you know if the recirculation flap is opening and closing correctly. I mean if you run on recirculated air won't the fans draw air from inside the cabin so there should be no wheezing sound? When off it will draw air via the intake above the bonnet?

IXLR8

I would have to go out and unplug that vacuum hose I replaced.

I believe the system is electro-vacuum operated.

Have a look at this A/C Repair thread in detail.

ToreB

It's easy to spot Zingari, just look up under the dash, you'll see the flap. Press the resirc button, and see the movement.
Cheers,
Tore

pcarhombre

Good catch, Alex. Next question- 5 mins to diagnose, how much time to replace?

ble2011

I seem to have a wheezing sound and lack of really cold air. I'm going to check all my vacuum lines. This post is most helpful. Thanks.

IXLR8

10 seconds, if that. Only because it was easy to access and we all know how easy it is to work on our cars.

IXLR8

Well you know if your A/C is working just by the temperatures of the Hi and Lo lines.