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I'm getting ready to swap the AC compressor on my 1988 K5 Blazer 350 V8 with a new unit. the old one has now started to make noises which forcast a breakdown soon, very soon. So I'm at that point where I have to pick another unit that will most likely die next year or the year after. Does any manufacturer build a good quality compressor ?
 

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That's pretty much a crap shoot on the R4s. I got a good one from NAPA but the air gap was way out so, I had to adjust it to spec (.020 - .030"). I had a new UAC that made noise all the time. Whatever you get, pull the orifice tube and inspect it for debris. If it has a lot of junk, you'll need to flush the system, replace the accumulator/drier and orifice tube as well as your compressor. Before you install the compressor drain all of the oil out of it and measure how much it has, if any. After a flush you'll need to add 4oz of oil in the compressor, manually rotate it until it turns smooth. Then add 4oz of oil in the accumulator. Assemble the system and suck it down, check for leaks and hold the vacuum for at least 1/2 hour, better to do it over night. Then add Freon (I'm guessing yours has been converted to 134a?) until the system stops taking any. Then start up the engine and let it idle for 5 minutes with the A/C on to distribute the oil throughout the system. Then you can top it off, you may have to rev up the engine to get the last bit in. IIRC, your system call for 20oz of 134a so, 3-12oz cans will work fine since you won't be able to totally empty them.

The A/C wiring for the early GMT400 trucks don't have a high side shutoff on the back of the compressor, originally that switch was wired in to close the recirculating door when pressures got too high. You should get a newer style HP switch that closes when under ~250PSI and opens when over ~350PSI and wire it in series with the low side circulating switch (next to the accumulator). I found this out the hard way when I started the truck after sitting a few minutes hot. The pressure switch on the back of the compressor blew out, sounded like a shotgun going off, scared the sh*t out of me. HTH
 

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Discussion Starter #3
Thank you, Yeah I'll bet I must of replaced 4 of these crappy R4 radial compressors, not on my Blazer, but other GM I've owned. The old axial units seemed to last forever, but they were heavy. So once again in the name of the future we get jammed with new technology, or just junk.
 

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I kind of figured you've been there, done that, don't wanna do it again! These compressors are really touchy, initial startup is critical for them. Wish you good luck with the parts swap gods looking down upon you! 🤞
 
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