Then last month I started it up after it sat all day, about a 95 degree day. Started it and just let it idle for no more then 1 to 2 minutes while I arranged my stuff before leaving. Then grunge/screech/smoke/smell and no more cooling - same thing again but I hadn't even sped up the engine. Immediately turned it off. Got out and looked, oil blown out all over the engine again. Turned it back on and the compressor spun freely, no funny noises, but no cooling. Unlike the first time, when I tore it down I didn't find anything much in the system, no little metal chunks, just a little bit of "blackness" to the oil, a small amount of sludge on the O-tube screen. The inside of the compressor did not seem to have any broken parts. From how everything looked I might have been able to fix it by simply recharging it but I had already ripped the compressor apart. So I bought all new parts again and redid it last week. Got a compressor, accumulator, o-tube and condenser from rockauto for $220. Now it's cooling fine.
Then about 3 days after fixing it I was at the SAME park where it had blown the second time. Started it up and heard what I thought sounded like the grudge noise - like the fan belt was just starting to slip and was fighting it. After having heard this twice before I immediately turned it off. Thought maybe, just maybe I smelled a tiny bit of burning oil but there was no smoke like the first two times. Drove about 3 miles to the store with the AC off and a frown on my face. Popped the hood and disconnected the compressor. Then started the engine and turned the ac on. Then plugged the compressor back in while I watched under the hood. Compressor came on, no funny noises, and it started to cool!! In fact, it seemed to be working perfectly normally. So I presume I caught it JUST in time before it blew out the high pressure blow-off again and spewed oil everywhere.
So at this point my thinking was that maybe I was putting too much oil in the system and slugging the compressor on start up. So I pulled the one week old compressor back off and checked the oil level. It was actually on the low side, certainly not at all overfilled. So put it back together and it's working just fine.
Sorry for the long post, ...
why is this system blowing up within 1 or 2 minutes after a "cold" start???? It's always in the 1 or 2 minutes when I would think the system isn't even working hard yet.
Every time I start the engine (and AC) now I have my finger ready on the AC on-off button ready to shut it off if I hear the slightest funny noise.
I put in 80% of the amount of R12 as I'm using 134a. Running it in the driveway at 2000 rpm I've seen the low side drop to 30 and the high side go to over 325. I don't see how they could possibly go even that high, much less to the 400 psi needed to pop the high pressure valve within 2 minutes after starting with the engine at or near idle speed.
Anyone got any theories? Too much oil? Too much refrigerant? Not enough virgins being sacrificed?