328 a/c high side fitting size

The high pressure AC fitting on my 328 has a 7/16" -20 male threaded portion. I believe that this is the same thread used on 1/4" diameter tubing flare fittings, and that is probably what the 3/16 or 1/4 designation means.

 

dhs-9 -- I think ric1241 mis-understood your question and gave the thread size of the actual main hose connection (not the port where you "screw on a gauge"). I think the R-12 gauge ports are the same size as a tire valve stem (but I'll check that), 1/4", since they both have Schrader valves inside -- take a protection cap off one of your tire valve stems and see if it fits.

Or just use a ruler and guesstimate the OD of the port thread (it's not a small difference so you should be able to tell).

 

You're right--the high pressure side is the smaller port.

DO you have a set of R12 (R22, etc) gauges? Or are you just going to recharge with a simple charging kit (wherever you may get your freon or substitute from)? You only need the high side port if you're using the full 3 headed set of A/C gauges--in that case, you'll probably need an adapter to connect to that reduced diameter high side as the gauge sets are set up for home (R22) systems in which both sides are the same size.

 

My bad here -- I just measured my TR (R12) and ric1241 had it right -- the external threads on both gauge ports are 7/16" x 20. I know my ex-308 (also R12) was the same (as I used the same gauge set on both) -- are you guys sure that other F models using R12 have different sizes for the gauge ports on the high and low sides?

mea culpa -- I throw myself on my oil filter