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Shakercars's 1972 Trans Am

2019 August
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Trying to charge my AC


Hello all. New to Pontiac. New to this forum. I have an 86 Fiero GT. I have no experience at all with this but, my AC wasn’t working, and it was the original R12 system. So I purchased a retrofit kit and a gauge set and here’s where I’m at. 

Originally there was no pressure at all in the system so I replaced all the O-rings on the accumulator and the orifice tube without worrying about recovering any R12. I then pulled a vacuum on the system for around an hour and then let it sit for a while and verified that the gauges held at -30. 

Using my manifold I put 8 oz of ester oil into the system and no leaks and it still held pressure. 

Then attempted to charge the system using 12oz cans I bought from parts store. Turned AC on high and hooked can up to manifold but refrigerant never leaves the can and the pressures never rise in the gauges. I’m getting power to the low pressure switch but the switch is not turning on the compressor relay. If I jumper the low pressure switch I can verify the relay gets voltage on the load and control side and I hear the relay click and the compressor clutch kicks in, but even then the system won’t charge through my manifold via the low or the high side. 

I get that the low pressure switch won’t kick on the compressor when it’s completely empty like it is, but I don’t get it how it supposed to charge it initially. Is it through just vacuum that it should pull from the refrigerant can? How can I get this system charged? I feel like I’m so close. Can anyone help? 



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