The original 1993 label (apparently designed in 1990) from the R-12 accumulator. Per TSB 94-19-20, the charge is now 2 lbs 6 oz (38oz) of R-134a, & 11oz (the original 7 plus 4 extra) of PAG-46 per TSB 97-10-05. For some reason, TSB 97-15-05 does not indicate the correct oil quantity.

After charging, the low pressure switch should be adjusted to turn off around 22psi for R134a. This TSB describes the setting for R12, but the process is the same:



A properly-modified R12 system converted to R134a should have a high-pressure switch as well.



Factory R-134a service ports use rubber balls (which are easily cut) instead of Schraeder valves; the conversion fittings are F3AZ-19E762-A & F3AZ-19E762-B.

A QUICKER & usually cheaper way to do this conversion is to find a '94-96 factory R134a system still sealed on a junk truck with the same engine as yours, and lift it out as a unit, including the underhood HVAC box, and the hood latch support bracket; and swap everything without opening either refrigerant system.

Owner caption November 2009 · Photo 53 of 434