re: climate control unit

[smith737]

I have a 1990 964 C4 and have just been experiencing a problem with my a/c. Everything seems to be working correctly (nice cold air), however without touching any controls, the air blasting out the forward vents all of a sudden dramatically reduces to almost nothing. The fan speed is still the same, but it sounds like the air is being diverted to somewhere behind the dash. Its not coming out the windscreen or floor vents and the controls for these are in the shut position. Is this a control unit problem or what?? Has anyone had this occur to them??

[Don Plumley]

Here's a good article on the various servos that tend to be the primary source of problems:

http://www.porsche964.co.uk/technical/servos.htm

[bigchillcar]

this is my 'new nightmare', don..lol. when i press the a/c button..no heary any clutchy kick on. don't know if a lack of or very low amount of r-12 in the system will prevent it from coming on (low pressure switch?). hoping that's all it is and not the $$$ control unit with all its fun servos..i'll be following this.

[smith737]

Thanks Don for the link, it certainly did help. Although not before the r/h side fan bearing decided to let go.
Man those things are expensive to replace!!! Here In Australia its about $500usd!!!
So its a fan replacement and a complete check of the servos whilst they have everything apart.

[MJR964]

Smith737, I have the same problem as you with the low flow out of the forward vents. I looked at the servos, and they all seem to function fine. Did you ever find out what the problem was?

[smith737]

Still working through the problem, seems to be alot of air coming out somewhere under the dash ( you can feel it when you stick your hand under there).
On top of that i've had both the l/h and r/h aircon blower fan bearings die on me. I had just replaced the r/h one and got it fitted when not a day later the l/h fan packed it in. (and its a hot summer down here!!!).
Will keep you posted via this thread.
Mike

[bigchillcar]

mike, my r/h one has a bad bearing as well. i'll hit the defrost button intermittently to spin it faster and then turn it off. sometimes it helps, but i need to do the job. did you do yourself? go through the trunk? how long did it take? i was told mine may just need lubricating the bearing. what are your thoughts and experience with this?
ryan

[smith737]

Sorry about taking so long to post again. I've been on holidays ( unfortunately not with my car)
Its been in the garage getting the aircon sorted out.
The r/h fan was replaced originally and it wasnt too hard to do. Although I did get it done down at my local workshop (great place called Eurotune).
However the l/h fan was not so easy. Glen, my mechanic, did about a 12hr job on it. The fuel tank needed to be removed!!! And so whilst that was out all the ducting and servos were checked and the aircon re-gassed.
It was a big job and cost me a bit too. However I now have an aircon system that is just like factory new!!

[Don Plumley]

Wow, that's a lot of work to r/r a fan. But I'm sure it's nice to have it all working.

Don

[bigchillcar]

well, my system won't hold much vacuum and then only for a few minutes at best. it's going in for a look see in a few days. hoping it's only dry o-rings, but fearing a bad evaporator with a leak. yikes. haven't priced a replacement yet.