Mr.Alex

About two months ago the CCU fan started making noises so I lubed it up with motor oil because had no graphite grease at the time. The fix worked for about a week till it started making noises again.

So the second time I took it out, I got graphite, but it was the powder, but I tried it anyway since it was all out already. This fix worked for a day and started to come back when I was on a mountain run under heavy turning.

So, is it all bad?

Or do I get some actual grease grease, because the powder might have gotten blown out?

Mr.Alex

no opinion :[

Vandit

I haven't messed with mine, but I hear it from time to time, and, yes, sometimes it does seem to be aggravated by aggressive cornering.

kos11-12

Hi guys,

Mine is doing the same, I will just get rid of it as soon as I find a way to take out the unit, as it is useless.....
It is there only to suc air into the CCU to analyse quicker the temperature of the air , but apparently it doesn't make a great difference if it's removed .....

ToreB

kos11-12, i don't agree with you at all.
The CCU fan draws air from the cabin over the interior temperature sensor. If there's no air flow due to a faulty fan or dirty sensor, the sensor will measure the air temperature inside the CCU unit. This gets HOT over time (an hour or so), and this will fool the CCU to think that the cabin is very hot. It will therefore adjust the opening of the mixer flaps to reduce/stop heated air coming from the engine.
The driver will notice this as reduced cabin temperature, and must compensate by turning up the temp control ****. You'll end up at the maximum setting, giving heat at full blast, or no heat at all when you turn it down.
If you use your 993 in warm environments only or just drive it for half-an-hour trips you could live without the CCU fan. If not, the CCU fan will need replacement as the electronics in it can fail, as well as the magnets are fading. There's also problems with wear on the needle bearings, this makes an annoying noise.
See my link below to the my Porsche HVAC pages.
Cheers,
Tore

boxsey911

Tore is right. I tried running without the fan and the cabin temperature kept swinging between hot and cold.

NateSaJack

I solved this noise the second time round by not only greasing (think I used vanilla flavoured Vaseline ... Don't ask!).

I spent a long time cleaning the little fins, they are separated by varying gaps and I found a cotton bud and white spirit did the trick.

I lot of muck came off. I think the weight of that muck caused balance issues which contributed to the whurring noise as much as lack of lube.

fuch

Bring back the sliders/cables like my old sc had....worked fine for me..till the wife got in the car & mucked about with them..bwarrrrr

ZG862

Wow, you must be a really sensitive driver! I can barely tell the balance difference when the fuel tank is full.

bmohr

ToreB - I don't doubt what you state, as it seems pretty solid advice, but I only wanted to add that I unplugged my fan and the temp works fine. It doesn't swing wildly back and forth. It is true however that if I want to go from hot to cool air(i have no ac) it does take the flap to switch positions a bit longer...maybe a minute or so at the most? So i agree it's not ideal, but I think it might be worth the shot if you are in the OP's situation to try to unplug it and see what happens. If it gets all wonky, just plug it right back in and look for the correct fix/replace.

ToreB

The air temperature in the cabin will not swing at all if the CCU fan does not work.
It will decrease over time as the CCU enclosure gets hotter. This rate of decrease (and if it happens at all) also depends on the ambient (outside) air temperature.
My experience is that an 1/2 hour drive in cold winter weather (-5 to -10degC) will be OK, and there's no need for adjusting of the temp ****. A two-three hour drive or more in this temperature will make you end up near maximum temp setting, producing a "binary" action on the temp ****. Either scalding hot (max heat from the engine) or ice cold outside air.

A missing CCU fan will not be that noticeable when driving in summer time, let's say around 25 degrees C. The CCU will have some problems regulating the cabin temp, but the temperature differences between A/C cooled air(7-10 deg C) (if fitted) and the ambient air temperature is not large. The user will probably like to have the cold air flow anyway.

Cars without A/C will not experience any problems at all in summertime, as the CCU will probably open the fresh air flap to max in the first place, (and both mixer flaps will of course be closed) and the increasing CCU enclosure temperature will not change this.

The problem is bigger when heated air is needed in the cabin, especially in winter time. There's a big difference in full heat (open mixer flaps) and ambient (outside) air. Regulation problems will therefore be more noticeable.

So, a missing air flow over the cabin temp sensor due to a faulty fan or dirt on the sensor will not make the air regulation go wonky, but you'll need to increase the temp setting along the trip. In long winter drives you'll be able to choose being very cold or very hot.
Cheers,
Tore

kos11-12

Tore,
I will follow your experience, my mechanic advise me to do so, maybe because it is quite warm here , even in winter...
By the way how do you remove the CCU ?
Thanks !

boxsey911

Thinking back, that was my experience too. Everything seemed fine with the temp at first but the car got colder as the journey went on.

Mr.Alex

As of right now I didn't know if I could leave the fan disconnected, so I just turned off the first fuse to the whole CCU unit.

I'm not sure what to do, but if I remember correctly that little fan is quite pricey.

Jacke2c

About four years ago, I tried something a little different. I rebuild post war Lionel engines and have learned quite a bit about small motors. We mix our own oils with graphite for the wheel bearings and I mean mix it really well.... But it did not work well on the little fan motor... I think it is the position, but my lube job lasted about a month, SOoo, I thought something that would hang in a little longer. So the next time I used a micro amount of CV joint grease that came with my replacement CV joint for my '79 SC (now gone to a new home). It is still working.... after four years the only problem is it is a little annoying because it is noisy when you shut the engine off and runs for about 10-20 minutes until it shuts tself off. Cheeper than a new one...