I have a 2000 C2 and the climate control system recently started acting up. Here's the details:

A/C blows very cold. No problems with compressor or related parts.

Vent selection has gone wonky. When I first start the car, I can select the center vent max cooling and max airflow and get very good cold flow from the center vents. It's very nice, and exactly what I'd expect, so I know it can work properly, which is a good thing. However, somewhere between 30 and 120 seconds after startup, some unknown action is initiated without my requesting it, a flap deep in the bowels of the system is moved, and I get almost no flow out of any vent regardless of what has been selected. If I turn the car off, I get another couple of minutes of good flow, then it clams up again.

No combination of manual settings/auto settings/vent selection/recirculation will prevent the system from apparently closing all flow off, but any combination I choose will work properly for the first two minutes or so. Turning the ignition off every two minutes and restarting the car is not really the way I wish to enjoy my very cold air conditioning, even if that option seems rational at times when it's 100 degrees outside.

Here's the list of non-stock electronics related modifications to the car, just in case there is any potential for crossover interference:

1) Fabspeed ECU.
2) Iphone jack wired into the aux input of the stock CR-220 radio.
3) Porsche Center Mount Radiator.

Bonus info: Occasionally, the left front speakers will cut out, and when they do, I get some alternator whine and whine from the radiator fans. I'm guessing there's a bad ground somewhere in there. Would any of the climate control system share a common ground with the audio system? Any input or suggestions for troubleshooting would be appreciated!

 

I recommend changing your ignition switch. Try playing with the position of the key and see if the HVAC starts to have a mind of its own.