[E28] A/C fix needed

["Aaron and Aimee Ness" <aaness@xxxxxxxxxxx>]

Since A/C seems to be a recurring thread right now...

My 528e seems to have a bit of a problem with the A/C - the compressor
engages, but I don't get cold air.  I borrowed a set of gauges and talked to
my parts guy (he owns an imports parts shop and tends to specialize in
European cars).  He has a replacement for R-12 that is supposed to be
environmentally friendly, more effective than R-12, and can be used without
any kind of special certification.  I'm not sure what substance it is, but
he has used it in the past on various cars of his own, including his Benz
that had leaked down to a point at which the compressor wouldn't engage.
When he refilled with this stuff, his idle speed no longer dropped when he
turned on the A/C and it blew cold.  But enough about the magic juice...

We hooked up the gauges, expecting to add some of that magic juice, and
although I don't recall the numbers (it's been about a year), it was reading
higher than expected on the high side, and lower than expected on the low
side, indicating a potentially clogged expansion valve.  I talked to a
reputable A/C shop and was given a price of ~$500 to replace the valve
(assuming that is the problem), suck out the R-12 (they won't give a credit
for R-12 removed), evacuate the system, and refill with R-12.  I believe
they also recommended replacing the receiver/dryer, although the PO had it
replaced at some point in the last few years.

So now my questions:
First, if I proceed with this work, how can I be sure nothing else is in the
system to clog the expansion valve once I'm done?

Second, how hard should it be to find a shop that will give me credit for
R-12 they remove from my system?  I have a hard time just giving it to them,
and then turning around and paying them $60/lb. for more.

I should note that I won't be going to that shop since I have moved.

Thanks in advance...

Aaron
'87 528e
'88 325is?
'70 Beetle
'82 GPz550

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