Reply to "Front AC condenser and R-134 conversion."

JT,

Here's a paragraph that's taken from the Vintage Air catalog:

"Compressor Capacity Is Critical
Capacity is critical in selecting a compressor.
Why? The weak link in most aftermarket
air conditioning systems is the condenser's
ability to handle the demands of the other air
conditioning system components. These
demands are to condense the refrigerant
enough to keep the compressor head pressure
and corresponding refrigerant temperature
within acceptable operating limits (approx.
twice the ambient temperature of the day, plus
fifteen percent) and to supply the evaporator
with adequate refrigerant. Generally speaking,
if a compressor has too much capacity the
result will be excessive high-side pressure and
temperature, compressor damage and excessive
load on the engine. If a compressor has
too little capacity the system will suffer inadequate
evaporator performance. Our basic minimum
given in the condenser part of this article
is larger than most aftermarket systems
are using; however, we will use that as our
standard size condenser. A compressor of 8
or 8.5 cubic inches of displacement per revolution
is ideal for a classic car or truck with
our standard size condenser, and an average
size aftermarket evaporator (approx. 200
cubic inches of coil mass). We would always
lean toward a smaller compressor before
going to a larger one."