Off the top of my head, 250 sounds awfully high for the fans to kick on for an R12 system. Some of this is starting to come back to me - there are two versions of the pressure switch, a green and a red I think. One of them is of R134A conversions, so you may have the wrong version of that switch. A search through the Tech Help archives should help you.

The fans are pretty noisy, so you should hear them in the cabin. Without them on, you're not going to get much out of the system.

That's the last I'll say about this one - will defer to someone who has more practical experience. Finally, (joking) your brother is an AC mechanic? Why the heck are you asking us questions?!!

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
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