The older A/C systems were marginal at best when run on R12.  I usually
use Freeze-12 on these systems to maximize performance of them and they
are OK when fully functional and charged.  They will keep the van cool
but don't expect any miracles.  The newer systems are much better
because they were built better.  They have a condensor in the front that
is probably twice the size of the old systems (key with 134a) the blower
fans move more air and the compressor is nicer (7 piston vs 5 piston of
older vanagons).

I have put R134a into a system that still had R12 in it and run said
vehicle for years and years with no negative effects.  It had a positive
effect of having cold air conditioning though :-)

Ken Wilford
John 3:16
www.vanagain.com

Bill Collins wrote:
>> If you have a later model
>> Vanagon (86-91) you can go to Wal-mart buy four cans in a kit and
>> convert the van in ten minutes.
>>
>
> What's the issue with converting older vans?  Not enough cooling capacity after conversion?
>
>
>
>> If the system still has a little in it then it
>> probably has just leaked out over time (normal) and you can recharge it
>> and it should last a while.
>>
>
> Are you saying that it works to mix R12 and 134A, rather than having the R12 recovered and then filling with R134A?
>
> Bill
>
>