[Vwdiesel] Re: R12 replacement

[bobs at chemdec.natsci.csulb.edu]

Seeing the post on R12 replacement prompts me to tell my AC retrofit
success story...

I recently did a complete re-work (R12 to R134) of the AC in my '81
RabbitTruck because it had a seized compressor.  Even if the compressor is
OK the procedure would be basically the same.  Here is what I did, some
was overkill:

1.  Had the R12 removed by a licensed shop.

2.  Since the replacement compressor was for a R12 system, drained all the
oil from it then re-filled with the proper type and amount of oil for R134
before installing.

3.  Removed and discarded the old hoses and dryer.

4.  Removed evap and condenser.  Because the compressor had seized there
was a lot of debris in the system, so cleaned evap and cond by flushing
first with water (yes water, even though refrig machanics say not to),
blew out water with compressed air, flushed with acetone (acetone combines
with and removes the water), blew out again with compressed air, replaced
in vehicle.

5.  Had new hoses for R134 made.  (Eaton Aeroquip EZ Clip hoses, see
http://www.aeroquip.com for details, pricy but I think worth it.)

6.  Installed new dryer, over/under pressure cutoff switch in line with
the compressor clutch coil, and new (R134 green) "O" rings all around
during reassembly.

7.  Borrowed high vacuum pump from work, pumped system for 48 hours
through guage set on new R134 ports.

8.  Removed pump and let system sit a week watching guages for pressure
rise due to leaks.

9.  Pumped another 2 hours before charging with R134.  R134 charge is
about 1/2 to 2/3 the original R12 charge.

I'm now getting air temps from the vents in the range of 34 to 39 deg F
with outside temps 80 to 90.

To do next is find a fan that will fit behind the front grill to cool the
condenser coil while in heavy traffic.


Bob Soukup
'81 RabbitTruck