AC ROOKIE W/ RECHARGE ISSUES

T

Tincture77

Member
I replaced the comprssor on my 73 t-all with a rebuilt 4 seasons unit (exact match except for slightly different high/low port inner seat). I drained out the oil from the new compressor and replaced it with an equal amout of pag 150 oil. I then flushed the system with cleaner (ac flush solvent) and blew filtered air through the system for 20 minutes (both condensor and evaporator sides) . I also replaced the drier with a new one. I hooked up everything and turned the a/c on, and the compressor clutch engauged as is should. I then attached the r134 can and adaptor to the low side (port with s on compressor) and pierced the can open with the needle mechanism and then turned the needle back. After gently shaking the can and moving it from 12-3 as described in the instructions nothing is coming out of the can into the system. I connected another can I had with the preattached gauge and after pressing the button the gauge read 100 lbs. When I let go of the button the pressure reads 0. What is going on?
 
Any time an ac system is disassembled and parts replaced it must be vacuumed down with a vacuum pump for at lease 30 minutes after reaching a hard vacuum.
Check and make sure the shrader valves are being actuated by the threading on of the adapters and recharge hoses.
 
Yup, definitely needs some time under vacuum before adding the freon. Since you've got some new components in the system, you might want to be sure the system is leak free and that it holds vacuum before you spend your $ on freon. If it holds steady for an hour with no detected rise on the gauge you're good to go. A slight rise May mean that the system is still out gassing moisture so do try to reapply the vacuum and test again.
 
The can will and should get cold while the refrigerant is taken in through the suction side of the compressor. The fact that the can gauge goes to zero means it is taking refrigerant just slowly. Depending on how sound the compressor and evacuation of the system is it May take a while for it to fill. If you are seeing a slow intake invert the can while you are running the compressor. You May want to double check the high and low sides of the compressor. The high side will get a tad warmer then the low or suction side while running.

Either way air and moisture are a big problem. The air is the biggest factor. The new filter drier will remove the moisture but cannot remove the volume of air. The air will not undergo the phase change (liquid to gas to liquid) that the refrigerant will and you will always have vapor in the liquid side of the system.
As they say "suck it before you blow it" (add refrigerant). :dita:
 
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