stevedowd911

This car is an early '95 993. As part of my AC fixing this summer, I found that the PO had pulled the AC relay (I found it laying around in the spare wheel well). I replaced it and my AC condensor fan worked again and I got some AC (not nearly as good as some of my daily drivers. but usable in the PNW...).

I was driving out to the track yesterday and thought I'd turn the heat on for a moment (short sleeve shirt on, weather system passing though....).

Didn't get any heat out of any vents. I changed the sliders, turned the heat **** all the way up on the CCU, still nothing.

Stopped to buy gas, and thought about the relay, as that was the only thing I remember changing since last spring. Sure enough, with it out of its socket, the heat works again!

Any clues on what might cause this? Is the CCU going a little nuts?

If it turns out to be too involved to fix, I may just have two seasons - relay in and relay out.

Thanks for any/all help!

993inNC

Is the little recirc button in the upper right corner of the ccu pushed in or out?

stevedowd911

Chris - Thanks for the reply.

I believe it is out, but I'll check tonight to be sure. Should there be a light on when it is pushed in?

Thanks!

stevedowd911

The recirc button is pushed out (so no light on).

Yet another symptom, with the AC relay in, and the car in my shop so I can hear stuff better, I noticed the AC condensor fan was turning on and off in about 2 second intervals. I noticed this because the lights on the dash were "surging" as the fan kicked on/off.

Methinks the CCU is a little screwed up. Does anyone know where these can be fixed?

Thanks

stevedowd911

Sorry, I meant to say the AC condensor fan was going on/off when trying to get heat in the car. Seemed to act normally with the temp **** set to the blue dot.

Lorenfb

"Methinks the CCU is a little screwed up. Does anyone know where these can be fixed?"

The 964/993 CCU is very reliable and rarely if ever fails. The CCU system needs to
have diagnostic tests via the Porsche Hammer or PST2. There're many other problematic
elements in the CCU system, e.g. relays, actuators, sensors, wiring, & etc.

vjd3

Easiest way to test it would be to swap it out for someone else's ... if your problems go away, there you go. In fact, you should try swapping the relay in question as well.

Vic
95 C4