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Posted: Jun 04, 2010 7:19:59 am
howardmarkallum



My heater / ventilator fan cut in at full blast and won't turn off, even with the ignition turned off. Eventually pulled the fuse but flattened the battery first! Any suggestions? Or am I going to have to replace the whole control unit? At the moment I can just drive with the sunroof open, but that won't be much good once the summer's over...
911 Novice

Posted: Jun 04, 2010 1:26:04 pm
Pete



Hi Howard

Welcome to the forum.

Can you tell us a little morte about your car.  What model is and year.  Hopefully we can help once we know what we are dealing with.

:agree:

Posted: Jun 04, 2010 6:34:23 pm
howardmarkallum



My car's a 1990 964 C2. Picture  attached.
911 Novice

Posted: Jun 04, 2010 6:40:04 pm
Pete



Hi Howard.  Thanks for that.

I cant see the picture.  I would recommend joining a picture hosting site and then embed the picture.

Why not join www.p101tv.com where you can upload pictures and videos etc, and then embed then back here, or anywhere else for that matter.  It would be nice to see a pic or two of your 964.

I'll also gove some thought to your heating problem.

Posted: Jun 05, 2010 7:51:55 am
Pete



Hi Howard

Please try www.p101tv.com.  Upload your pictures there and then embed them here.  I've done it this way to save server space for the forum.  Its very easy to do...

Pete

Posted: Jun 05, 2010 2:04:57 pm
howardmarkallum



This is definitely the last attempt!





Hooray!!
911 Novice

Posted: Jun 05, 2010 2:31:17 pm
Pete



Hi Howard - congratulations.  You posted a pic.  Its easy when you know how  :agree:

She does look nice.  How long have you had her?  Have you done much to her?

Anyway, we should try and fix your heater problem.  Did the heater stay on after you switch the fan on and then it wouldnt go off, or did it just come on then stay on?

Posted: Jun 05, 2010 6:42:56 pm
MarkJ



Hi Howard, great looking car, very very similar in look to the one i had for 4 years, always great in Black. Looks like it needs lowering a tad though ;) 964's always sit high IMO. A 911 should never have gaps around the wheels !

As for your heater, hmm, not sure whats causing that. I would recommend trying the guys on the Rennlist 964 forum. There is a good Brit contingent and it may be a fix someone has the answer to or has experienced before. Otherwise you could try trawling through the Pelican forums using their search engine for words like heater etc.
Good luck !
Sprightly 1134kg and falling.

Posted: Jun 06, 2010 9:44:17 am
Pete



My feeling is that there are three potential areas to investigate:

(1). The heating control unit.  They are pretty simple units and there may be a short circuit.  They are not too tricky to remove and inspect.  A straight swap would be the cure.;

(2) A short in the blower unit.  Accessible from the front luggage area, its a bit of a pain to get to.  This is less likely to be the problem, but worth a look;

(3) a short in the wiring loom from the control unit to the blower assembly.  I think their is a four/six pin plug at the bottom of the blower unit. 

I cant be much more helpful than that, but investigating the above should help you isolate the problem.

Posted: Jun 06, 2010 4:41:34 pm
spenner



Another possibility is the engine heat sensor, if it tells the control unit the engine is still hot even after the car is turned off it will fire up the fan in the engine bay to blow air over the motor, at least it does on the older 911 like my 1981 SC (I studied the heating system a lot to fix mine) an excellent diagnosis is in 101 projects for your 911

Craig

Posted: Jun 11, 2010 4:35:38 pm
howardmarkallum



It seems that the problem lies in the final stage of the control system which is a little box of electronics fixed to a great big heat sink up against the firewall. The part is £410 = VAT in UK, but I've found one on eBay in the USA for $125.00
911 Novice

Posted: Jun 12, 2010 8:07:53 am
Pete



Quote: howardmarkallum at Jun 11, 2010 4:35:38 pm
It seems that the problem lies in the final stage of the control system which is a little box of electronics fixed to a great big heat sink up against the firewall. The part is £410 = VAT in UK, but I've found one on eBay in the USA for $125.00



Glad you found the problem Howard.  It always seems cheaper to get parts in the USA.  I gues the exchange helps too!


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