Discussion
Just bought a 993 and trying to understand how the heater works. I can only get cold air out of the left side footwell, face level and screen vents regardless of the temperature settings and volume slide controls. Right hand side does all the right things. Any ideas anybody? Thanks in advance, Brian
Hi got same issues om mine, there are several small servos under scuttle that are prone to failure. try watching them as someone alters the mix. try this site http://www.porsche964.co.uk/ and click on technical tab then electrical repairs image then heater controls at the bottom of page.964 has same sys as 993.
hope this helps Dave
hope this helps Dave
brian7136 said:
Just bought a 993 and trying to understand how the heater works. I can only get cold air out of the left side footwell, face level and screen vents regardless of the temperature settings and volume slide controls. Right hand side does all the right things. Any ideas anybody? Thanks in advance, Brian
If its the non A/C version, take a look in the drivers instruction manual. I remember with mine, it was illogical the way one should position the levers!HTH
brian,
get the car out on the drive with both doors open & front seats extended as far back a s possible.
take out the over mats (if there) & fold back the footwell carpet sections
there will be a (sort of) 3 dimentional carpet section at the top of the footwell running from the centre console down to where the door opening is on either side. take both of these out on each side, they are held by two visable posi screws.
you should now see each sides air ducts (orange flexi tubes about 3" in diameter that lok like robbie the robots arms)
in the middle of these ducts there are two servo controled units (in black), one will have the motor head visable & the other will have the motor head up towards the dash.
these servo's open & close to allow the flow of air up into the dash board & can fail. with your heater system running (easier with the engine off) move your heater positions from hot to cold & make sure bith servo's are opening.
try both sides it is very clear to hear them opening & closing-the motors make a whirring noise.
if you find one is not working don't panic just yet (they aint cheap), undo both servo's from the hoses unplug the connector & switch them over. obviously if the faulty one isn't working again you need a new one.
if the side that wasn't working fails with the servo that previously was operating it's a resistor on the heater control unit (the stereo shaped control box in the dash that dictates the flow of hot & cold air)
there's a guy on 911uk who has the circuit diagrams & it should be a cheap fix for any auto electricain, it's a common fault.
do the motor test first to determine where your fault lies (as described above it shouldn't take longer than an hour for even the most inexperienced) befor eyou start ordreing expensive parts, iirc the heater control units are usually £500 second hand & the servo's are £400 new from porsche though don't quote me on those figures.
get the car out on the drive with both doors open & front seats extended as far back a s possible.
take out the over mats (if there) & fold back the footwell carpet sections
there will be a (sort of) 3 dimentional carpet section at the top of the footwell running from the centre console down to where the door opening is on either side. take both of these out on each side, they are held by two visable posi screws.
you should now see each sides air ducts (orange flexi tubes about 3" in diameter that lok like robbie the robots arms)
in the middle of these ducts there are two servo controled units (in black), one will have the motor head visable & the other will have the motor head up towards the dash.
these servo's open & close to allow the flow of air up into the dash board & can fail. with your heater system running (easier with the engine off) move your heater positions from hot to cold & make sure bith servo's are opening.
try both sides it is very clear to hear them opening & closing-the motors make a whirring noise.
if you find one is not working don't panic just yet (they aint cheap), undo both servo's from the hoses unplug the connector & switch them over. obviously if the faulty one isn't working again you need a new one.
if the side that wasn't working fails with the servo that previously was operating it's a resistor on the heater control unit (the stereo shaped control box in the dash that dictates the flow of hot & cold air)
there's a guy on 911uk who has the circuit diagrams & it should be a cheap fix for any auto electricain, it's a common fault.
do the motor test first to determine where your fault lies (as described above it shouldn't take longer than an hour for even the most inexperienced) befor eyou start ordreing expensive parts, iirc the heater control units are usually £500 second hand & the servo's are £400 new from porsche though don't quote me on those figures.
toreB's website with handy hints & pics
(plus those wiring diagrams for your auto electrician)
http://privat.bluezone.no/toreb2000/ccurepair.html
(plus those wiring diagrams for your auto electrician)
http://privat.bluezone.no/toreb2000/ccurepair.html
Thanks Cragswinter. Right side footwell servo/flap opens and closes as you would expect, left side stays closed regardless. Swapped the servos over and the fault stays on left side, so it seems I will have to look at the control unit. I will follow up your link to the guy on 911uk. I'm no electronics engineer, do you know of anybody who repairs the control units professionally? Thanks again for your help. Brian
Lucky!
As I said it's the servo flaps that are the expensive part. From what I've heard it's a very basic job, though as always with things like this I'd rather find an experienced auto electrician whos worked on units like these back in the day.
ToreB will probably help you out (but he is in another country so sending the unit to him may be a hassle & unnecessary expense) but if you show his diagrams to your auto electrician they should be able to fix it for a relatively modest price.
Ask toreB nicely & he may suggest which resistors to check 1st
As I said it's the servo flaps that are the expensive part. From what I've heard it's a very basic job, though as always with things like this I'd rather find an experienced auto electrician whos worked on units like these back in the day.
ToreB will probably help you out (but he is in another country so sending the unit to him may be a hassle & unnecessary expense) but if you show his diagrams to your auto electrician they should be able to fix it for a relatively modest price.
Ask toreB nicely & he may suggest which resistors to check 1st
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