[s-cars] No heat diagnosis please

[Sam Clarkson]

Thanks Vincent
I've had a play around and managed to get everything working fine,  
then I put the TCMA back in and nothing!
Now I have no voltage to the TC motor. But there was voltage before.  
Potentiometer reads fine.
Any ideas where the next point of weakness might be, I haven't  
touched the main head unit yet, I guess a bad plug connection there  
might be an option.
Any swappers are many many km away.
At least I've  got the lever manually over on the hot position now  
till it's all sorted.
Sam Clarkson


On 19/06/2007, at 2:30 PM, Vincent Frégeac wrote:

> Hi,
>
> I would start with voltage to the motor. Testing is fairly easy  
> once the
> servo (TCMA) is out:
> - Open the servo but leave it connected, remove the motor without
> disconnecting it (for easier access), move the arm in midway  
> position, clip
> the voltmeter probes to both wire on the motor, turn the start key  
> to on (no
> need to start the engine) and set the temp to LO. Check if there is  
> voltage.
> Then set the temp to the highest temp and check if the voltage  
> reverses.
>
> Testing the potentiometer is easy too:
> - Disconnect the servo, open it, remove the center gear (the gear  
> that pop
> off by itself) then use a voltmeter to test the resistance between  
> the left
> or right post and the center post. Make sure the resistance vary  
> smoothly
> when you turn the arm.
>
> If there's no voltage on the motor, I would first try to swap a  
> known good
> HVAC control unit. If you don't know any one close with either a C4  
> A6, a C4
> S6 or a 90V6, try to find one in a junkyard. There rarely fail so  
> you should
> eb able to have one for very cheap. Use this write-up for the HVAC  
> unit
> swap: http://www.audifans.com/twiki/bin/view/Audi/ConsoleFrontC4,  
> only the
> steps 3 and 5: A 10min.job including the beer at the end.
>
> If the potentiometer doesn't work well, or not at all, turn the arm  
> fully in
> one direction (the direction is irrelevant as long as you turn it  
> fully so
> it doesn't contact the center section) then slide a 400 sand paper,  
> sand up,
> between the contactor and the potentiometer to clean the contactor.  
> Use only
> a very fine sand paper or you'll make the contact surface rough and  
> it will
> destroy the resisting strip in no time.
>
> Sorry, no idea how to reset the HVAC codes without a VAG-COM.
>
> HTH
>
>
> Vincent.
>
>
> -----Message d'origine-----
> De : s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com] De la part de Sam Clarkson
> Envoyé : 18 juin 2007 20:20
> À : s-car-list at audifans.com
> Objet : [s-cars] No heat diagnosis please
>
> Hi all
> 93 S4
> No Heat, I pulled the codes; 08.7 temp regulator flap sporadic block
> and 11.7 central flap sporadic block.
> I've pulled out the temp control motor assembly no movement as I
> cycle through the temp range. The arms all move freely and smoothly
> with the TCMA out and heat comes on/off when moving them manually.
> The motor in the TCMA goes fine in both directions when directly
> connected to a battery.
> Any advice as to what's next to test.
> The potentiometer? How?
> The supply to the TCMA? How?
> How do I clear/reset the codes?
> Getting the TCMA out is a BITCH on a right hand drive car, just in
> case you care!
>
>
>
> Sam Clarkson
>
>
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