I’ll share with you an idea I did on an 89 Chevrolet 3500 crew cab dually I have when I did mine. Let me just throw out some ideas and observations on this.
I didn’t like the way it cooled. Stock system with what they called an HR6 compressor. It worked but just like it was too small. It was. I looked it up. The old A6 was 12.54 cubic inches. The HR6 was half that at some 6.1 cu in capacity. It went away.
After I got the brackets for the old A6 for the 454 it was about to be on. Now everyone I ever heard that went to r134 just said the stuff don’t cool as good or it didn’t seem as R12. But the question I had was why? The new cars and trucks seem fine. Well I found the answer. Most people that converted from 12 to 134 kept their original condenser and flushed it or replaced with an exact new replacement.
Problem there is near every R12 condenser was a “tube fin” condenser. All the 134a stuff built after 1992 or so has a parallel flow condenser. It’s much much more efficient than the tube fin and the engineers knew this.its true that 12 is a better refrigerant but, it’s not that much better if you look at the data compared to 134. The reason the factory 134 cars did good was because the engineers understood that 134A needs a better heat exchanger(condenser) to get rid of the heat quicker. Hence the parallel flow condenser.
So I found one that was nearly same dimension as my original but a parallel flow version and installed it. Then I got to thinking… my truck has an orifice tube and gm used the white one. I see they have like 5… well turns out the difference is the colors and the orifice diameter of the holes. White is .072 ford used a blue one and it’s .067. So I put the blue one in.
Drew a vacuum on he thing and let it set for couple hours and no leaks. Charged it with R12 and I guarantee you that’s the coldest damn ac I’ve ever been around. Correct amounts. Never freezes up. Perfect normal operation.
Center vent air temp on the 3rd speed is 31/32 degrees in n end of July here.
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