[V6-12v] A4 air conditioning

[Tom Leppke-Hennig]

I would like to add some information to this discussion on the 134a
systems in the b4 and b5 cars. Other Oodis are probably same/similar; I do
not know.

The system is filled through a high-side fitting on the condenser. First,
the system is drawn down to a known quantity of zero pounds-ounces of
134a. Then, the specified weight of 134a is pumped in using the
recovery/filter/pump systems that all legitimate A/C service places have
now. Using the manifold gages to read the performance of the system, like
in an r12 system, is of limited value in a 134a system, so they are filled
to a specified weight and that is it. Be really careful to not jury-rig a
can to attach to that high side port. With the compressor running, the
system pressure will blow the can.

Rigging a can to go in place of a low side switch, or adapted to the
low-side of the compressor, however, should work fine. But, draw the
system down to a vacuum first, then add the correct quantity.

I know there are plenty of anecdotes out there about people topping-up
their system with a can or two of 134a from the FLAPS, and getting better
cooling. But if you really want the system to perform, charge it to the
specified weight.

Tom LH
1995 90q