A/C repair

["Aaron Ness" <aaron@xxxxxxxxxx>]

My parts guy has some "stuff" (I don't know what it is, but supposedly it is
a direct replacement for R-12 that is CFC-free and fully compatible with
R-12 in the system) that he was going to let me use to recharge my A/C in my
E28.  I borrowed gauges and last night we hooked them up to try and get the
A/C working.  It turns out it wasn't actually discharged, but based on the
fact that the high pressure side reads higher than he expected to see, and
the low pressure side was slightly negative, he suggested there may be a
blockage in the system, most likely at the expansion valve.

If possible, I'm inclined to have the system discharged (maybe I can get the
shop to pay me for the R-12) and replace the expansion valve myself, then
take it to him and have it filled with the R-12-compatible refrigerant.
However, Bentley says several times that the system must be evacuated to
remove any moisture before charging, so I expect I would have to take it
back to a shop after I replace parts, and hope I replaced the right parts.

First, does the diagnosis sound reasonable?

Second, has anyone had a similar problem?  The receiver/dryer was replaced
within the last few years by the dealer before I got the car, although I
don't know if this has much relevance.

Finally, assuming this is the correct diagnosis, does anyone have a ballpark
guess on a cost for the repair at a shop, considering that I have a full
charge so R-12 would not need to be added?

This mystery refrigerant is something he bought to use in his M-B, which
runs R-12.  He said basically all the charge had leaked out because he
always forgets to run the A/C in cold weather, so the seals dried out.  He
refilled it with this stuff, and he said his idle, which used to drop about
150 rpm when he switched on the A/C, now remains steady because this
refrigerant is supposed to have better thermodynamic properties than R-12.
I'll find out specifically what it is,but for now, I'm just requesting input
on my situation.

Thanks in advance...
Aaron
'87 528e
'82 Scirocco
'70 Beetle
'87 Jeep Cherokee 4.0 - for sale

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