AC Compressor: HR980

grumpin wrote

Aftermarket or dealer installed?

mat in tn wrote

true. having ford on the label means it's from an earlier ford maybe. I did not notice what year the truck is. possibly get a picture of the duct box on the firewall also and we should be able to see if it is a factory or dealer system. even the 1983 that I'm restoring had a different type of compressor than that. ac systems are basically simple but can be finicky or even complicated to get correct. it is not just a case of add more freon. to make it more complicated, when added to a car/truck engine it becomes a "variable response" which is magnified by a variable environment. epa regulations changed who and how freon can be bought, sold, transported and installed, due to it being labeled harmful to the air and ozone. oddly enough they had to use transport across state lines to get regulation passed.  
another variable item known to complicate things is the thermostatic expansion valve (txv) it works like a variable jet to control the flow of freon to the evaporator core (inside coil). the compressor creates pressure and the txv regulates it. another is the desiccant canister (filter-drier) also known as an accumulator. when a system sits too long empty, the desiccant absorbs moisture until it is saturated then must be replaced. any system which leaks down to the point of zero pressure can begin to draw in moisture from the air and condense it in the desiccant.