A/C only works on lowest dash control

[mrmambo]

We're getting ready to head to Florida for Thanksgiving and I thought of trying the A/C, which worked fine all summer here in Atlanta. When I tried it yesterday, though, it seemed to only work on the lowest dash fan control (position 1): the AC switch lights up, the clutch engages, and the coolant fans both come on. But if I switch it to 2 or higher, the light goes out, the clutch disengages and the fans go out.

Plus, on position 1, I don't feel much, if any, air coming out of the vents, with or without the AC switch on.

I've tried reading thru Dan's very detailed A/C and fan diagnostic document on the forums here, but can't see anything that seems related. I checked all the relevant fuses and they look okay.

Any ideas?

Thanks-

-Mark-

[mrmambo]

It looks like 2-3 other users here have had the same problem:
- one thought it might be the A/C control switch on the dash and was looking at an eBay repair service
- another user fixed it by replacing a resistor located near the glove box that had been corroded by water backing up from clogged drains (a problem I suffer constantly)

Any ideas on which resistor this might be and how I could get to it?

UPDATE 1: I tracked down the resistor myself; it's VW Part #1J0-819-022a, blower motor resistor. I found it for $26 (plus shipping) at CompressorWorld.net
I followed the other directions on this forum, which instructed you to remove the glove box. Once done, though, I found I simply could've unscrewed one plastic fastener holding the black felt-like cover underneath the glove box. There you'll find two small bolts to remove which hold the resistor assembly onto the bottom of the blower motor.

I could see rust and corrosion when I opened the relay area, plus water came out of the black felt-like cover. The cover is flush against the resistor, so any water that makes its way in there from blocked drain plugs just sits against the relay and corrodes it. Great design overall. :-(

Will let you know if that fixes it--part should arrive by Monday.