A/C compressor screech

[Wallace White <whitew@leland.Stanford.EDU>]

I'm almost finished with my cross-country trip and the 5kcstq is doing
well, though it gives me cause for concern sometimes. The A/C compressor
makes an unpleasant, half-second screech most of the time it engages at
highway speeds. 3000 rpm is the breakpoint: below that, it's silent, and
above that, it's pretty regular. But since we're driving through Montana,
it's a shame not to take advantage of the "reasonable and prudent" speed
limit.

Reading channel 14 on the climate control, I can watch the high pressure
side temperature cycle, the compressor disengaging around 120 F and
engaging around 95 F, every thirty seconds or so. (Glad I brought the
Bentley along for the trip.) That's at a little over 80 mph, maybe 3100
rpm. There have been no fault codes, except an occasional 07 for the
stupid flaps that aren't working right, but I'll worry about that later.

How concerned should I be? I just had the system charged last week (back
in Rhode Island) and it's been good and cold since then. I hope I'm not on
my way to a new compressor. Thanks for all advice, as always.

- Wallace White
  '87 5kcstq, 145k (and rising fast)