[s-cars] Heater core and seat switch

[Theodore Chen]

I finally got my '92 S4 to pass smog.  It turned out to be a bad fuel pressure regulator, resulting in a few psi too much fuel, and cost me a few hundred dollars to the mechanic to diagnose and repair.  I had tested it with a MityVac during my troubleshooting and it seemed to be operating normally, but apparently it wasn't opening fully.  I wish I'd just replaced this $75 part as a matter of course.  Collateral damage from the faulty FPR was the catalytic converters, which I replaced to the tune of $700.  Then it passed smog with flying colors, producing numbers far lower than I've seen in the whole time I've had this car.

After a few weeks of enjoyable motoring, the heater core began leaking.  Now I have a few drops of coolant coming out of the ducts under the dash.  I went to the dealer to order a new heater core and got this part number:
443 819 030
This also matches the number provided at this link:
http://forums.quattroworld.com/s4s6/msgs/142607.phtml

However, on Audiworld somebody posted a list of part numbers and this was the part number for the heater core:
http://forums.audiworld.com/showthread.php?p=18985290&highlight=heater+core#post18985290
443 819 031c

I'm a little concerned about the discrepancy in part numbers, but the dealer looked up the part number in their system and ordered it already.  I'll also order part 431 819 225 - heater box gasket (seal between box and bulkhead).  What else should I replace while I'm in there?  The blower motor was replaced at about 50k miles, years ago.

I also have to figure out how to get the heater core out, which leads me to my next question.  One of the posted procedures involves removing the center console, which requires moving the seats to get to the screws in the sides of the console.  My passenger seat won't go forward, although it goes in any other direction.  So I pulled the seat and now have the switch in my hand.  I'd like to test it to verify it's bad before I go get another one, but am not sure which pins to check.  Anybody know how to test the seat switch?