Climate control box - was air out center vents only

[Mike Arman]

> 
> The vaccum servos inside the AC programmer are suspect, in my opinion.  The
> rest of the circuitry on the board in the AC programmer (behind the dash)
> seems to be pretty well thought out, but as much as I hate to say this to
> you I wonder if you've got a marginal vacuum servo in there, causing the
> thing to go into defrost mode sporadically.

> I wish someone would supply replacements for those vacuum solenoids.  They
> are really pieces of crap, and if we had a reliable source of spares the AC
> systems on these cars could be kept running without much trouble.


Air out the defrost vent only is the default - if the CC box fails, this
is the fail-safe. Dig into the CC box . . .


These are Delco solenoids out of mid-90s vintage large body GM cars -
Buick, Olds, Caddy, etc. The controller box is under the dash on the
right side (sound familiar?), you can get the whole box with four
solenoids, the one-way valve and the vent flap motor for $5 or so at any
pick & pull.

It isn't a direct replacement, so you have to de-solder and re-solder
the solenoids onto the PC board. The actuation lever on the flap vent
motor is different, but the Audi lever fits the shaft (press off/press on).

When you are looking at the CC box, check the following items - cold
solder joints on the solenoids - these are wave soldered, which means
the big parts don't get hot enough while the little parts tend to melt.
Fix with a soldering pencil, 30 watts or so is fine. Check for split
hoses, and sometimes the check valve breaks in half or clogs. Blow
through it - air goes one way, not both, and if it goes both ways or no
ways, the valve should be changed. There is also a loop of hose that is
too long and rubs on one of the components in the box - it wears a hole
in the hose and you won't see it unless you lift it out and look for it.

Don't try moving the actuator lever on the flap motor - this will strip
the gears. With the box hanging loose, work the CC head and the motor
should run. There's also a service bulletin about soldering a 3.3K or
6.8K resistor (I think - values are a guess - can't find this) across
the position sensor potentiometer to keep it from hanging up on "dead
spots". Lubricate the flap cable - if it is stiff, it will strip the
cheap, fragile plastic gears in the motor.

Finally, check the vacuum hose tee from the inlet manifold plumbing (on
type 44 it is against the firewall behind the engine, runs over the top
of the heater box, disappears inside), sometimes the hose just falls off
one of the vacuum motors and you'll get air out the defrost vents only
because there isn't any vacuum to run the CC box in the first place.

I'm surprised I remembered all that about these things, it has been a
few years since I've done this ;-)

Best Regards,

Mike Arman
1990 V8Q

It isn't a car, its an adventure!