Re: Seat Heater Control Switch

[Porsray@aol.com]

I am presently in need of a heater control switch out of a late '80's/
early '90's 80/90/100/Coupe Quattro (little rotary dial switch that
plugs into center dashboard). 

Ray Calvo (porsray@aol.com)
1990 Coupe Quattro
<<<<<<

Fixing the lamps in these switches is on my TBD list.  A cursory examination
of
the switches in my 1988 90Q failed to reveal obvious lamps.  Perhaps Ray can
explain his disassembly procedure.

***                 ...Kirby    (Kirby A. Smith)                 ***
***              ksmith1@mailgw.sanders.lockheed.com             ***
***              [=]   kirby.a.smith@lmco.com                    ***
***  Opinions expressed herein are entirely those of the author. ***

Ok, Kirby, but don't say I didn't warn you.  This is NOT a fun job!

1) Remove switch from dash by prying out with a screwdriver (as you pry,
will also disconnect harness from switch.

2) You will see an outer plastic housing that covers the circuit board,
   red plastic housing, and rotary dial.  This housing can be pried
   off by inserting thin screwdriver blades under the sides of the
   switch (should see little prongs sitcking into the sides of the
   housing that have to be pried free).  Pull out the housing
   SLIGHTLY, then lift out the two metal bars at the top and bottom
   of the switch that act as the catches to hold the switch in the
   dash.  Hold the switch so the side of the dial faces up (circuit
   board is down), then slide the housing off.

3) WARNING - BE VERY CAREFUL OF THE ROTARY DIAL.  DON'T DISPLACE IT
   OFF THE RED PLASTIC HOUSING!  There is a microscopic (almost)
   steel ball that acts as the switch detent; if you lift the dial
   off the red plastic you'll lose it and never find it.

4) Now, the red plastic/dial unit has to be pried vertically up away
   from the circuit board.  You might be able to pry the legs of the
   red plastic out of the locating holes in the circuit board, but
   in my case they broke off  (no major problem; the outer black
   plastic housing will hold everything in place on reassembly).

5) With the red plastic/dial assembly out of the way, you can
   unsolder the old bulb and solder in a new one.  Recommend the
   German OSRAM model 2721 (2mm W X 4.6mm H, 1.2W); haven't found
   a US bulb that matches (type 73 is just slightly too wide, as I
   remember).  Pry the wires away fom the new bulb, and sand/file
   the protective coating off the leads (these are actually designed
   for a plug-in application, so leads have anti-corrosion coating).

6) Can check for functionality by hooking a 12v power source across
   terminals 3 and 5 (see back of switch); bulb should light. MAKE
   SURE OF CONTACTS if you do this; this is how I fouled up and blew
   the rheostat.

7) Reassembly is a reversal of removal (yeah, right)!  After the switch
   is all back together, when you try to reinstall it, you'll finid
   there's no way to hold the harness in place to force the switch
   contacts into the harness.  In my case I removed the radio, then
   held the back of the harness in place with the short end of an
   Allen wrench while I pushed the switch into place.

Have fun!

Now, that I've said the above, WHO'S GOT A GOOD HEATER SWITCH????

Ray Calvo (porsray@aol.com)
1990 Coupe Quattro