79jasper
Chickenhawk
I was flipping through a book to our JD 624 looking up some torque specs and came across the ac section. It has you add a can right off the bat before you start any testing. Even walks you through flow testing the compressor. Found some of it quite interesting.My buddy who does my state inspections in PA, his father used to run a garage, they would occasionally work on AC and there was a "lazy way" his dad would work on his own ac stuff that was R12 originally but needed to be 134a. First jump the low pressure switch and see if the compressor will spin at all, second jam a can in and see if you can get any pressure to read without blatantly leaking out as fast as it's going in to make sure you don't have a legit rust hole. If that works, add ester oil into the system before filling any further to swell the seals up some and put in enough cans to get the ac to operate even if it isn't perfectly efficient. Run it this way for at least an hour so the oil can circulate and get absorbed some near any dry seals. After this, purge the system (I'm not advocating this part or any of it really), the moisture will come out of most of the system if there was any with whatever else was in there. Then add pag oil, only half the amount the system calls for and fill the system with 134a until the compressor stops cycling with the R12 pressure switch, no more than 8 oz after the system stops cycling.
I will admit that though this isn't the "right" way to do this, when I got my first IDI and hadn't learned to do things right yet, I tried this only from knowing about it from a story he had told me about his dad half assing stuff sometimes... and it's the coldest AC I have. Colder than 2 systems I replaced everything and did totally correct. I'm not saying it's because this method is better, but I think something can be said for some of the older ac parts on our truck being more stout and compatible with 134 than we give them credit for sometimes. I think a new clean orifice valve, and a clean system with good working pressure switches is the most important part.
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