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RE: '84 5k A/C controller curiosity
Thanks for the controller primer Mike. I haven't had central vent air in =
my 87 5KCST for a while and you inspired me to start digging.=20
This where I'm at so far:=20
--recirculator flap works fine: replaced seal
--The controller motor is fine; I can see it move smoothly
--As you said, I took the circuit board out and shook it, all the =
solenoids *seemed* to rattle; it's hard to tell for sure though
--I put vacuum directly (with hand pump) to the flap actuator(the =
thingy with the internal bellows and lever arm) and it DID NOT hold =
vacuum. It tried to move the lever but wouldn't hold. It seems to me =
that this piece is bad. Has anybody BTDT on this one? P/N's? How hard is =
it to R/R?
Not much inside. Usual problem is the solenoids get oil in them (runs up
the vacuum lines) and the rubber seals swell. Quick test - remove
controller box, remove PC board, shake - if it rattles, it is OK. No =
means swollen seal, that solenoid is bad. Note that EACH solenoid must =
The little vacuum distributor disc also has a rubber one-way valve in it =
also usually swollen shut - blow through it - no air means no good.
Of course, you can't buy the individual solenoids from Audi. Visit a
u-pull-it junkyard - this is a GM part - found in GM large cars
(Cad-Olds-Buick) of 1990-ish vintage - entire controller box costs $10
there. Take it apart, unsolder good (rattly) solenoid from GM board, =
it into Audi board.
Other things to check - cold solder joints on solenoid to PC trace
junction, stripped gears in motor (use the GM motor - make sure you =
the little actuator arm before you pull it off).
Save the disc-shaped vacuum distributor, too - you'll need it.
Failure modes: Only defrost works - no air from center vents - =
Clicking or ticking from programmer box when temperature changes - motor
and gears (the gears are plastic and strip easily.)
There are usually other problems here as well - fresh air recirculator =
arm is often broken - remove plastic panel over A/C and wiper motor, =
in and wiggle recirc door (this is on the pass side of car) by hand - if =
flops easily, the arm is broken. Repair part available from Audi or from
parts car, major PITA to get to - mostly tough to reach - skinned =
For a while, I considered fixing programmer boxes "on the side" - the =
lack of response led me to believe I should keep my day job . . . so I'm
now giving away what I can't sell (no nasty comments, please - you know =
you are . . .) <G>