Several problems all related to a 91 420sel.

Replaced compressor, oil, complete flush, new expansion valve, drier, hose assembly, O rings, valves etc. - everything. Using R-12.

1. The pressures on the low side are a little high (55psi) and I was wondering if the expansion valve is not set for R12 but for 134a might be causing the problem?

2. When charging, as I approached 1.5 lbs of refrigerant in the system, the bubbles cleared up. I stopped and checked the performance. It was good. I continued to add the additional 1.4 lbs as per the specification and the pressures were high and the cooling was not as good as it was at 1.5 lbs. The high side was 275 and the low 50-55. I removed 1 lb. and it performed better.

I am questioning the setting of the expansion valve and I wonder if they are not factory set for 134 and it does not allow full performance when using R12.

What do you guys think?

They are adjustable and I am considering setting it to reduce the low sire pressures.

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I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k