The AC in my 85 GT had leaked down over the winter.  It hadn't been serviced in over six years, and was short cycling before it quit, so my first thought was just a natural loss of refrigerant.  The best move would be to convert to R134a, but I wasn't ready to do that right now so I checked out some of the alternative refrigerants available.  I decided to try Enviro-Safe, one of the HC alternatives.  There is a lot of discussion over the safety of HC refrigerants, so research it for yourself before going into it.  I've also been told that professional shops will not work on a system that has had HC refrigerants used, so take that into consideration.

I'd done AC maintenance before, and this process isn't all that different.  If you don't know what you're doing, stop NOW because you could hurt yourself.

Remove the plastic cover over the AC plumbing.  The little valve on the accumulator is the low pressure port.  The high pressure port is low on a tube by the bottom of the spare tire.

A buddy loaned me his refrigerator compressor based vacuum pump.  You can also rent them, and Harbor Freight has a air compressor powered venturi unit available for less than $10 (I've heard they work, and have bought one).  Pump a vacuum on the system to dry it out (we're assuming that there is no
Freon left in the system, since you would probably have to have it removed at a licensed station).

Almost ready to go.  The new bottles use a new type tap, and the old low pressure fitting needs to be retro-fitted with a quick-connect type fitting.  The low pressure fittings come with their own schrader valve, and you have to remove the schrader core from the old screw on fitting before installing it.  Naturally I had pulled the vacuum before I knew this.
Pulled the core and screwed on the retro-fit quick connect fitting.  I gave it one last twist for luck, and twisted the threads out of the supplied aluminum quick connect and off of half of the low pressure port as well!  Walked away from the job for a week.

Returned with a replacement low pressure quick-connect retro-fitting.  This one was brass and luckily the thread engagement was twice the length of the cheapo fitting that came with the kit.  I managed to clean up the threads and get it seated properly.  Fiasco averted.
Other waiting traps were that the screw fitting on the delivery quick connect fitting was loose as delivered, and if you screwed the delivery hose too tightly into the can tap fitting, it would cut off all gas flow!  Check out the tools very carefully.

Just about ready to go again.  Low pressure fitting fitted, vacuum drawn then relieved, high pressure gage in place on high pressure port.

I really didn't need to short the low pressure cutoff, since loading the first can was enough to raise the pressure above cutoff level.

I loaded a little over two cans, and that gave me sufficient pressure on the high side.  Nothing to show (and I was too busy to take a photo while I was doing it) so here it is all buckled back together.  Read the spec sheet and don't overcharge.  I believe the correct amount should be 2.2 cans, but the stuff loads so quickly it would be very easy to overcharge.  Two cans may work just fine.

I've been told it may also be worthwhile to add 2 oz of oil if the system has leaked down.

Cool! Summer 2002

It's Spring 2004, and still blowing cold.

Here's the stuff.

I got mine at
autorefrigerants.com

Here's their Spec Page on the product

revised 4/25/2004