A/C Retrofitting

["R. Cummings" <cumm@flash.net>]

>
>Just today I saw an R-134a retrofit kit for sale at a local parts store.
>The kit simply had a hose, two fittings, oil, and two cans of 134a, all
>for $26.95. Since I own a formerly R-12 car (I say formerly because all
>the freon is gone), I was interested. The kit makes no mention of the
>reciever/drier or flushing and pulling a vacuum. This left me asking
>"could it be this easy..."
>
> Here are my questions:
>
>1. Is it necesssary to replace the reciever/drier?
>
>2. What can happen if I don't?

Since your system has a receiver/dryer, I assume it is a Coupe GT. R/D's for
the Coupe GT are $25 at our local A/C parts house. It is best to replace it.
The R/D contains the molecular sieve material that absorbs moisture from the
system. The moisture gets into the system by leaking through the hoses and
connections. Once the desicant is saturated, acid can form and in some cases
the material will disintegrate, be circulated with the refrigerant and plug
the expansion valve. If the R/D is relatively new and the system still dry,
it is probably compatible with R134a and does not need to be changed. 
>
>3. Is it necessary to flush the system, and how can this be done.

No, in the beginning of R134a it was though that the system had to be
flushed to remove all R12 and mineral oil but the recommended procedure has
changed. You do not need to flush.
>
>4. How important is it to evacuate the system?

You must evacuate the system to eliminate non compressible gas (such as air
or nitrogen). If you don't, the head  pressure will go sky high and the
performance will be terrible.

>I was figuring I could at leat blow out the system with a big can of
>Dust-off (nitrogen), but beyond that, I'm lost. Any help would be
>appreciated.

Don't bother. If the system is low on charge, you need to find the leak and
repair it. Then evacuate and recharge with R12 or R134a.

This is typically not a do-it-yourself project.

Bob Cummings - 87 Coupe GT 120,000 mi