L31MaxExpress
I'm Awesome
I have been fighting an issue for numerous years with my AC. I assumed it was just high head pressure cutting the compressor with a completely heat soaked interior and engine compartment in really hot weather. For years my a/c has cycled multiple times during the initial cool down and seemed slower to cool down than when the van was new years ago. This is most noticeable in my case while driving in city traffic under 45 mph. At idle it would cool fine as well as at highway speeds. Atleast one parts supplier has a wrong part number listed as a replacement for our Vortec trucks, suvs and vans. The high pressure switch in the back of the compressor is listed wrong. Several suppliers list a Purple switch (35972) as the Replacement for an OEM Purple, Blue, Red and White switch. The Purple switch cuts the compressor entirely too early. I finally hooked manifold gauges to the van, routed them behind the hood and taped them to the windshield and took it for a drive. I was expecting to see sky high pressures when it cut the compressor. Instead the pressures were barely nudging 280 psi. The CORRECT Blue switch (35974) cuts the compressor off at ~430 psi. I bypassed the switch then re-tested. The ac gets ice cold within a block or two and stays blowing cold. The pressures peaked out around 300-325 crusing at slower speeds and 350 briefly under heavy acceleration at higher rpm. I will be changing the switch later this weekend. If you have rebuilt your ac or had it rebuilt and it seems to short cycle and slower to cool than you remember, check the color of that switch.
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