Hello,
I have a '91 240 with A/C that according to PO was converted to 134a. It works but recently started to short cycle so I'm figuring it needs more gas. The problem is I have experience on a lot of different R12 systems I've owned but not the 134a style. I have gauges, etc. On the initial quick look I saw a blue plastic cap on the accumulator LO side so I unscrewed that expecting it to be a dirt cap over a Schraeder valve of some odd new different thread size ofr something. Well..nope..it blew off and outgassed for a second while I scrambled to get that bleepin thing back on.. I did NOT see any external threads around the metal fitting, and I think what i saw was a groove ring but not certain. Also, the blue cap DID screw back on and seal OK without much torque needed and I didn't want to strip that so well enough was well enough. My question is if this is the new fangled normal fitting to expect and if so how do you attach or detach a gauge hose to work on these? Any help appreciated greatly and I WILL post final results. Hope somebody can get me up to speed on these fittings and thanks for any suggestions.

Dave in Tucson, Newyankee
'91 240
'87 240DL
'88 240
'91 245SE
'88 240 to be rebuilt
toooo many need fleet insurance
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Genesis 7:11