Short under the dash?

[Taylor]

Hey Audifans,

Here's the situation, '89 200 on the interstate with an outside temp of 
107F, 75MPH on a slight upgrade with A/C on, oil temp just a tick under 
130C, coolant temp just a tick over the first "dot" near the 3/4 mark on 
the temp gauge.  I have no idea if the 3rd stage fan is going, I can't hear 
it with the A/C blowing and radio/road noise.  The volt meter is at the 12 
mark, much lower than it has ever been even with the 2nd stage coolant fan 
running.  So I *assume* the 3rd stage fan is on.

 From under the drivers side dash, I hear what sounds like a shorting 
sound.  It is not constant and during the shorting sound the volt meter 
flicks back and fourth a small bit... looks like something is shorting out 
indeed.  I turn the A/C off, suffer for the next four miles to the next 
exit as everything appears to be normal, the oil temp drops, the coolant 
temp drops to below the half way "12 o'clock" point.  I can't see anything 
wrong visually with the engine, smell nothing and even though it is hot as 
hell... the engine is still at normal temps (upper normal range at least.)

Get back on the highway, turn the A/C back on and soon everything is back 
up towards to about where they were before but I notice no shorting or any 
strange movement in the volt meter.  I'm on level ground now or slight 
downgrades and I don't believe the 3rd stage fan ever came back on after 
that...

SO, could this be an A/C relay problem or 3rd stage fan problem?  The car 
has not been in such extreme conditions before... living mostly in cooler 
climates here in Orange County, CA.... oil is Castrol Syntec 20/50 if that 
matters.

Thanks...


--
Taylor
'89 Audi 200
'01 Audi A6 2.7T

PS.... two days prior it was under even more extreme conditions, big 
upgrade hill, A/C on, 80MPH, 98F, headlights, oil temp just a tick over 
130C, coolant between the "dots" steady at the 3/4 mark.  No shorting noise 
there at all.