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RE: '87 5KCSTQ HVAC temperature control motor--bad gearbox

I can address the heater flap control motor issue since I just went thru 
that exercise. What I have found is that one of the gears among many in the 
gear box of the motor loses several teeth. The gear appears to made of cast 
material and is quite soft. I collected four motors from the junk yard and 
found three of the four to have the same defect. The bad news for 86 + 
owners is that the gear box is sealed, whereas on the earlier units, three 
screws can be removed to get at the gears. I have found no replacement for 
the gears but I did find that it was possible to salvage one of the good 
gears from a defective unit to replace the bad gear on the unit being 
refurbished. That is not as simple as it sounds because the gear that goes 
bad in these motors is unique; i.e., there is only one gear of that type in 
each unit.  Now bear in mind that there are two parts to each gear, a thin 
large radius and a thick small radius. Thus with the help of spacer whose 
diameter is less than the smaller gear section radius, you can substitute 
one of the other gears taken from a salvage unit. The result is that you 
lose about half of the tooth contact on the thicker gear section, but I 
have found that the motor rebuilt this way works quite well under 
mechanical load.

I did a quick and dirty search for a new motor and came up dry; however, I 
did not check a GM dealer. I contacted Delco to try and get parts but they 
gave me the run around. So in a pinch you can try the junk yard approach, 
you might get lucky as I did and find a good motor, but the odds are not 
too good. Hate to sound selfish, but I am not giving up my refurbished 
motors. The Audi programmer has been too much of a pain in the ass. I 
figure I have that problem covered for the life of the car and its going to 
stay covered.

Good luck.

-----Original Message-----
From:	Evans, Nicholas [SMTP:nevans@geology.state.va.us]
Sent:	Friday, December 11, 1998 5:27 AM
To:	'quattrolist'
Subject:	'87 5KCSTQ HVAC temperature control motor--bad gearbox

Clearly this is the season when everyone is trying to make their heater
work & I'm no exception......the little gearbox driven by the small DC
motor down behind the glove compartment (that operates the cable that
operates the various flaps that are supposed to render the interior of
the car comfortable whatever the conditions outside) seems to have lost
a tooth on my car.  It skips a notch about midway through its travel,
with the implication that the cable does not extend or retract as far as
it's supposed to.  Now this condition is not as serious as some that
have been reported on the list: I can bias the thing toward heat or
coolness by adjusting the position of the cable sheathing under the hood
(I can set it so I get plenty of heat, but the heat doesn't fully turn
off when I dial down the temperature setting; or I can set it for cool
wherein I don't get full heating when I want it).  But this is silly,
and I'm into fixing things.  Not having taken one of these thing apart
before (I'm only about 3 weeks into my relationship with this car), is
the gearbox serviceable separately from the motor (not likely)?
Assuming it's not, given that this is a GM-derived system, is it
worthwhile to try & go through GM for a replacement motor/gearbox?  Or,
does anyone out there have a good used unit they'd be willing to part

TIA & Regards,

Nick Evans
Mayflower Garage
Barboursville, Virginia

'87 5KCSTQ