GTV-6 aircon woes

[Joe Elliott <jee@xxxxxxxxxxxxxx>]

So I noticed a couple weeks ago that my GTV-6's once mighty air 
conditioning didn't seem to be working as well as it used to.  I 
essentially confirmed this last weekend when I had 3 passengers in 
the car with me and one of them bought a bag of ice at a fuel stop 
and hugged it until it melted.

I tried to recharge it tonight.  I started by discharging all the 
refrigerant slowly so I wouldn't lose any oil.  Then I pulled a 
vacuum, which it didn't hold.  Eventually it would hold a vacuum so I 
assumed I got all the moisture out of the system.  Although the 
retailer of my magic hydrocarbon refrigerant says not to do so as you 
risk overcharging, I went ahead and charged it from a vacuum (doing 
anything else would admit humid air to the system, I thought).  When 
I did this before (and it worked) I didn't have a service manual so I 
put two cans of the stuff in the system (supposedly equivalent to 
36oz R-12) and charged it to a low-side running pressure of ~40psi. 
I've since aquired a GTV-6/Milano service manual which calls for 32oz 
of R-12 and doesn't give a running pressure,saying only that it 
should be between 12psi and 35psi when the thermostat shuts off the 
compressor. I was seeing pressures more like 50psi after shutting it 
off manually (it only cooled to 13C) and 35psi when it was running. 
I was also seeing more bubbles than ever in the sight glass.  So I 
let out some refrigerant so it'd be 35psi when it was off.  None of 
the bubbles went away and it didn't get any more effective.

So I discharged it to roughly atmospheric pressure and tried again. 
Basically the same result.  I know several people on this list have 
used this refrigerant without any instruments and just charged until 
the bubbles went away.  So I added a little more refrigerant, but the 
bubbles didn't seem to be going away.  What's the matter?  Could it 
be my compressor?  The condensor didn't feel very hot, for what 
that's worth.  Has anyone used this ES-12a hydrocarbon stuff with 
gauges and know what pressures they used?

Thanks,
Joe Elliott
'82 GTV-6
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