York compressor fittings expained
by Patryk Rebisz

More than a year ago I desperately search for answers trying to rebuild my car's AC. I knew it needed a York 210 compressor and that the compressor needed fittings, but beyond that - I was clueless and made many mistakes that cost me money. To spare you, dear reader, self-depreciating comments, here is an explanation of possible fittings for your York compressor.

The AC system has low side (blue cap) and high side (red cap). The low side (blue) has smaller service fitting but larger diameter hose, while high side (red) the opposite: large fitting and smaller hose. If you replace the hoses then match the hose to compressor fitting, but if you are like me, recycling the old hoses then you must use whatever was already installed in your engine. In essence York compressor comes with an assortment of different fittings, most popular being Rotolock and Tube-O
(the Tube-O on the left, and two Rotolock on the right in picture below):

The Rotolock fittings are not created equal - the ones that have silver finish are superior to those with yellowish finish. The silver ones - with nut closer to the valve itself - simply tighten easier because of the way the cap attaches to the service valve thus you don't risk destroying the connection on the valve when trying to torque it down - don't ask how i know it...
(see my attempt to make the yellowish fitting work below - failed soon after - notice that both fittingshave blue cap so the comressor is missing a high side service valve in this setup):

The fittings come in two hose connection sizes (#8 smaller and #10 larger diameter) with flare (the 45 deg connection) or without. Those that come without flare could be easily transformed with a small adapter ring (and a gasket). Fittings often also have build in permanent service valve - 13mm for low (blue) side or 16mm for high (red) side, or just have screw in connection. Some Rotolock fittings come with old-school shut-off valve. Make it simple on yourself and get as complete fitting as possible to avoid running into problems of matching parts and componnets.

In my case both hoses for high and low side had #10 connections (the the compressor picture above) and thus I had to get #8-to-10 adapter - the black part on the high (red) connection. (This of course introduces yet another seal - thus fail point.) In a perfect world I would replace the hose with proper fitting size for the high side (#8).

Searching for "rotolock fittings" or "york compressor fittings" you get all sort of solution so you have to be careful to consider:
-- if you need rotolock or Tube-O
-- that the fittings you are getting are the sort with nut closer to the valve (silver) = easier to tighten
-- if the hose fitting needs flare or not
-- what type and size hose fittings are on your car already (thus if you need 8-to-10 adapter)