kenh
I see nothing I hear nothing
Well at least so far.....
When I bought my 90 short bed I knew the compressor had the high pressure switch broken. The guy said the AC worked. Well you can run the compressor without the switch. I did and the compressor seized. I never checked but assumed it was an 134 system but was in fact R12. Found a kit at Advance auto to convert to R134 and got a deal on it through my work place. IIRC it was $192. It included compressor, drier, orifice, o-rings and oil.
I changed all the parts, flushed the lines condenser and evaporator with lacquer thinner followed by an approved AC flush. I have a vacuum pump but it is intended as a medical device used to suck up fluids. It will only pull a max of 20 inches but for this 17 was the most. I got it to use for some composite work when building my RC airplanes! Anyway... I let it evacuate the system for a couple hours, let it set and watched the gauges for leaks and the vacuum held steady. I pressurized the system and let it set. I may have accidentally on purpose loosened the wrong fitting and lost the charge in the system....... So back to the pump for another hour. This just helped make sure all the air was out of the system.
When filling an R12 system with R134 the rule of thumb is 75% to 80% of the R12 capacity. Another site said R12 times .9 then subtract 1/4 pound. My original system capacity was 2.5 pounds so 2 pounds is the calculated capacity. I only had 24 ounces on hand so put that in. I couldn't find my thermometer to measure the actual air temp but it's cold enough to give you a headache!
I intend to have our mechanic at work put our machine on it and pull a proper vacuum and then play with the charge a bit to optimize it. You have to have enough refrigerant in the system to carry the oil around to lube the compressor. R134 is not as tolerant of over or undercharge as R12 is so it may take a little experimentation to find the opitmum charge.
This all turned out better than I hoped. Time will tell if it stays this way.
Ken
EDIT: I back flushed the condenser so as not to push any debris from the compressor further into the condenser. I filter the discharge and found nothing in the flush fluid so am very confident of a clean system.
When I bought my 90 short bed I knew the compressor had the high pressure switch broken. The guy said the AC worked. Well you can run the compressor without the switch. I did and the compressor seized. I never checked but assumed it was an 134 system but was in fact R12. Found a kit at Advance auto to convert to R134 and got a deal on it through my work place. IIRC it was $192. It included compressor, drier, orifice, o-rings and oil.
I changed all the parts, flushed the lines condenser and evaporator with lacquer thinner followed by an approved AC flush. I have a vacuum pump but it is intended as a medical device used to suck up fluids. It will only pull a max of 20 inches but for this 17 was the most. I got it to use for some composite work when building my RC airplanes! Anyway... I let it evacuate the system for a couple hours, let it set and watched the gauges for leaks and the vacuum held steady. I pressurized the system and let it set. I may have accidentally on purpose loosened the wrong fitting and lost the charge in the system....... So back to the pump for another hour. This just helped make sure all the air was out of the system.
When filling an R12 system with R134 the rule of thumb is 75% to 80% of the R12 capacity. Another site said R12 times .9 then subtract 1/4 pound. My original system capacity was 2.5 pounds so 2 pounds is the calculated capacity. I only had 24 ounces on hand so put that in. I couldn't find my thermometer to measure the actual air temp but it's cold enough to give you a headache!
I intend to have our mechanic at work put our machine on it and pull a proper vacuum and then play with the charge a bit to optimize it. You have to have enough refrigerant in the system to carry the oil around to lube the compressor. R134 is not as tolerant of over or undercharge as R12 is so it may take a little experimentation to find the opitmum charge.
This all turned out better than I hoped. Time will tell if it stays this way.
Ken
EDIT: I back flushed the condenser so as not to push any debris from the compressor further into the condenser. I filter the discharge and found nothing in the flush fluid so am very confident of a clean system.
