Re: Seat Heater Control Switch

[Hans-J Tannenberger <hans@sequent.com>]

Hi,
this is a very good description, just one thing to add.
To my surprise Radio-Shack sells a perfectly sized replacement bulb
12 V Micro Lamps in a (2) pack  Cat No 272-1092B
It only took me 5 minutes per switch.
Hope this helps
- Hans


> 
> 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         
> 
>