I know this subject has been beat to death, but I haven't been able to find an answer I could understand to this specific question, so thanks in advance for your patience.

Just bought a '91 240, 171k miles, built with an R12 A/C system. It cools well but short-cycles at speeds above idle, like 3 seconds on-3 seconds off, most noticeable under increased loads like a hill. I've been trying to find the "spyglass" that other posts have described to have a look at the R12 level, but I can't find anything like that in the position described (to the right of the radiator on the pax side, nor on the left.) What I do see, behind the pax wheel well, is a tall round tower, black on the bottom, silver on the top, with three big hoses running out of it. At least one outlet connects with the compressor through a thick rubber hose. There are a couple of fairly large valve-type covers that unscrew. There are no stickers anywhere under the hood to indicate that a conversion to R-134 was done. The tower does look newer than most of the rest of the engine compartment.

What do you think? Also, if it is a conversion, is there no spyglass like in the R-12 system, or is it somewhere that I'm not seeing?

Scott
'91 240 171k, '92 745t 240k