mrsystems

This my 5th 911, 3rd 993, each of them had something, these cars really do have their own personalities, don't they? 3 different 993s and each of them different in so many ways. I am loving this my newest one although the defroster is acting very peculiar. Sometimes it blows simply by pressing the defroster switch. Other times it blows only after the switch is pushed in AND the fan is turned on. Still other times, it blows, then it stops on its own, takes a bit of a rest, and blows some more. Sometimes it whistles and then it'll spit up some very thin black substance that looks like tape? Quirky! Thus far its not not blown and is doing what its meant to do defrost the windows, although i gotta think something isn't right, any ideas as to what that might be?

ToreB

A damaged or unconnected (fuse) rear aux fan will force the Climate Control Unit (CCU) into a fault mode shutting down the front interior fans. This will produce the action you describe with intermittent blowing fans.
Whistling or wheezing noises may be caused by non-working air flow control servos (maybe the fresh air intake control) or resirculation flap (vacuum operated)
Have a look here for details:
http://www.ccu.tore.bergvill.com/
Cheers,
Tore

Arena993

This is a timely thread as I have a similar issue. My fans (especially when applying throttle) will cut in and out. At idle everything seems to be fine. I put it in gear and take off and the fans cut out. Now at cruising speeds I don't seem to have it happen. Any thoughts? Does the load of applying throttle cut out the fans? I am at a loss all AC, heat, air distribution and fans seem to be functioning properly except when applying a throttle load.

Mike

aribop

Mine also does the turn on and then takes a rest for a bit and then kicks on again. Not a big deal so far. I'll get to it sometime but not a major concern for me.

Arena993

Airbop,

So do you know the fix, or just waiting to delve into a diagnoses? I would like to repair mine since the driving season is right around the corner. I really don't use the CCU much since I have a cab, but I do like it to function properly.

Mike

Mike

aribop

Hi Mike,
Have not gotten in to it yet. This will probably be one of my summer projects...

mrsystems

Thanks Tore looks like you're familiar with this all right, I'll likely pass along this info to my mechanic later in the week. Any idea approx how many hours a job like this might take? I imagine that could vary widely depending on what is found. I'm also wondering if i just ignored it, since it does operate, would it likely just get worse and then fail altogether? I'm guessing yes? I doubt i'd be able to ignore it like a lotta P Car drivers i like my car dialed. Thanks again!

Warpig

I have a similar issue... with the AC on and the fan blowing during forward motion at cruising speeds all is well... If I drop the hammer the blower goes silent until I get off the gas. With the heat, when I put the car in reverse the blower blows at full speed no matter the dial setting when I come out of reverse the blower goes to low speed no matter the setting. While moving forward with the heat on it seems as if the blower speed #'s mean 1 - Really Slow, 2 - only a micro hair faster than really slow, 3 - just a hair faster than that, 4 - just a hair faster than that but still slow. When in reverse the blower blows FAST and hard.

I dont have a manual... anyone know how this crazy ccu is supposed to work?

Nick

mrsystems

Hey Nic yes, I had two other 993s before owning this one and those had CCUs that worked flawlessly. They basically did exactly what they were supposed to do and did it very well, no problems, no quirks. My mechanic says a lot of these cars have units that do not work flawlessly so perhaps i just got lucky on the previous two, dunno. He also mentioned that being the car is air cooled that that also contributed to its not being the best for consistent problem free performance. He spent a few hours on mine, took it out, took it apart, cleaned it up, put it back in and it seems to work about, the same so short of replacing the whole CCU i doubt mine is going to work any better, hope you have better luck!