I saw lots of bubbles in the sight glass, so I went ahead and add 8 oz. of R12 to the system. After adding the R12 the vent air wasn't much colder and there were still a lot of bubble activity in the sight glass. I put my hand to the low pressure hose and it wasn't cold, more like ambient temp. The high side was very hot and I then noticed that the auxiliary fan wasn't running, but it has worked in the past. After shutting down the engine, I put a jumper on the aux fan and it worked, could it be a relay?

Does the aux fan affect vent temps?

Does anyone know the book time to discharge a system, do a leak test and then refill? Can the recovered R12 be used again, or does it have to be fresh?
I have 14 oz. of R12 left, and I'm not sure if I want to continue the guessing game.

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'81 300SD