[s-cars] HVAC code gurus please

[Vincent Frégeac]

Hi Sam,

8.7 is the Temp Regulator Flap , sporadic block. Sometime it work, sometime
it doesn't, which is what you experienced. When it doesn't work, you'll get
the same mix of hot and cold air whatever the setting, except for Low. In
that case, the coolant valve shut off so it's a mix of cold and cold air.

11.7 is the Central Regulator Flap, sporadic block. Same thing, but on the
flap that direct air either on the dash vents, or on the Footwell/Defroster,
which is another flap: 13.

For each of these flaps, if you select the channel just above, 9 for Temp
Regulator, 12 for Central Regulator and 14 for Footwell/Defroster, you will
get the setting the HVAC is requesting, the channels 8, 11, and 13 should
show the same values as the channel just above when the flap work.

To access, the Central Regulator Flap servo, you must remove rear and front
center console plus a bunch of various bits so if you can live with it, just
leave it the way it is until you get a static block (11.5)

The Temp Regulator Flap is much easier to access. There is a detailed write
up here: http://www.audifans.com/twiki/bin/view/Audi/ServoMotorC4. If you
have some knowledge in reconditioning electric motor, the servo is easy to
open (a few Torx screw then pry it open) and, most time, it's just the
brushes that need to be cleaned. If you want to test the motor, use 6V max,
12V will burn it. A 4.5V battery works just great to test these motors.

And, if you want to become a HVAC codes guru yourself, read this:
http://www.12v.org/maintenance/index.php?section=tr&ss=hvac&ch=ccodes&v=1

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 : 16 mai 2007 20:54
À : s-car-list at audifans.com
Objet : [s-cars] HVAC code gurus please

Hi
93 S4
I've had no heat for a while, when it first went awry i'd have heat  
on all the time unless I went to full cold, even half a degree above  
would be back to full bake. Then no heat at all. I just checked the  
servo motor it's going. Vac is sucking and is holding fine when the  
motor is off. When I suck on the heater tap servo hose it opens and  
closes fine.
So I start the car and warm it up to pull codes the heater is now  
going!? What happened I didn't change anything?
Codes read ch1; 8.7 and 11.7
The 8.7 said to read channel 8 so depending on the temp setting in  
the cabin the readings on ch8 varied a lot.
The 11.7 said to read ch11 it read a steady 23.2 regardless of temp  
changes.
Anyone able to coach me on what's going on?
How do I clear the codes to get a fresh set of readings? Or is that a  
bad idea?
Audifans fan as always....


Sam Clarkson


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