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Yeah your calculations seems spot on and man is your system performing incredibly well. I'm jealous because I would be more than happy to get even 55F at 2000rpm.
It wouldn’t hurt to double-check and see if the actuator is adjusting correctly. It’s behind the ashtray - pull the glovebox to see it. There is a notched position indicator dial on it. As you adjust the temperature, watch to see that it rotates smoothly from roughly 11 to 1 o’clock positions.
OSC 4721 is what is in my 99 Tahoe, provided they are still being built the dimensions spec'd on RockAuto's site. I went through 3 different condemsers for the 87 G20, all built wrong, before adapting a replacement for a Peterbilt into place. The one I adapted into place on it covers the whole radiator opening in the core support plus a bit on each side. Back to the OSC 4721, still listed as a 34-7/16" wide core. Compared to the smaller core, should drop your high side pressures atleast 30 psi in the same ambient temps as it has a lot more surface area and can help shed more BTUs to the airflow through it. You really need to get the high side pressure under 250 psi at 2,000 rpm and the low side needs to get down close to 30 psi for the system to cool well especially with R134a. If you used a White orifice tube and if you open up the system, get a Four Seasons 38887 Yellow orfice tube. Then whatever you do make sure the condenser does not have one in the outlet as many are shipped with one in place there.
Another good point, although I would also check the recirculate one as well. In high heat and humidity that one can result in poor performance as well. Switching between recirculate and outside air should make a very noticeable difference in both vent temps and blower noise. There are ambient conditions here in Texas that I have experienced as much as a 10-15F increase in temps switching to outside air from recirculate. The more ambient humidity and the hotter it is outside, the bigger the difference recirculation makes. I actually often use outside air to reduce the cooling at highway speeds even in the middle of summer.
OK will check this out. thanks for the tip.
Will be ordering these asap. Thanks!
This stuff works well to cover your suction hoses as well. I usually also zip tie it at regular intervals to make sure it stays in place. The stuff GM wrapped the suction hoses with falls off in chunks after a few years thanks to the heat it is exposed to. It is what is wrapped around the suction hose from the accumulator to the compressor on the 1987 in the picture.
