Michael Robinson

I was just about home when I began to have an issue with the cabin HVAC blower/fan unit.
After some investigation I have narrowed down to the blower speed not responding to the CCU (Climate Control Unit).
Here are my symptoms: A/C compressor (on/off) and temp responds to the selected variables. All baffles function and direct air where selected. The issue issue I am having is I cannot control fan speed and if I turn off the climate control unit as a whole the blower will still run. It turns off the a/c compressor but just blows air. If I leave it off it will intermittently change speeds or stop but comes back immediately.
Could this be the result of a failing CCU, resistor, stuck relay, battery or the common ignition switch?
How many of you have experienced this issue? I am baffled by the problem and it seems likely it could be any of these.
I disconnected the battery in hopes the CCU will reset it self over night.

On a side note. about 20 minutes after noticing the blower these three CEL lamps illuminated for a brief second: PSM, ABS, and Brake all at the same time and never came back on. I ran durametric and it did not display any fault codes.

Related or unrelated.
Thanks for your help and input.

1999 996 Carrera 4
98,000miles

5CHN3LL

This was the very first symptom that my ignition switch was going south.

With the car started, try turning the key VERY slightly - 1 or 2 degrees - CCW and see if the fan starts behaving again.

Your car will act as though possessed by demons as the switch deteriorates further.

Michael Robinson

I have read about the ignition switch keeping the HVAC blower off but nothing about keeping it running or not being able to change speeds. Would a faulty ignition switch do what i described?
I did not explain that the blower will stop with the ignition power off (function normal).

5CHN3LL

What you described is precisely what mine did as the first symptom of the switch failing.

DBJoe996

I am casting a vote for the ignition switch as well. Same symptoms, same problems, same solution. Just do it!

alpine003

It's easy to jump to a faulty ignition switch just like a IMS diagnosis(or misdiagnosis).

I'm gonna say blower resistor on this one based on the symptoms.

dwebb944t

Yea but what kind of oil is he running, ask yourself that Jack!

mcbit

Just blame M1 because its recommended by Porsche.

5CHN3LL

Alpine, 5 bucks says the ignition switch. You in?

The Germans managed to miniaturize every electrical gremlin that has plagued British cars since the dawn of the internal combustion engine and entomb them in that damnable switch - I think it's a security feature intended to discourage reverse-engineering. Once they start to get out...

5CHN3LL

Crap, my replacement ignition switch had an Audi logo on it. Does that mean my IMS is going to fail?

alpine003

Sure, why not. I mean $5 would let us drive a few spirited miles, right?

alpine003

Unfortunatley, this is going to be the norm moving forward. Same thing with Lamborghini's. Kinda cheapens the fact that you pay $150k++ and you find Audi logos everywhere.

Now wouldn't be too bad if I found Lambo logo's on Porsche parts but then reliability would probably suffer.

mcbit

Yeah, but they'd be a lot more expensive if Porsche had to make all the parts.

alpine003

You mean they're not already expensive enough? :lol:

wwest

Battery....