AC Conversion

[David]

I'm converting a car from R12 to R-134a and I have a couple questions I hope someone might know the answers to.

#1
I've picked up a new can of oil for the system, but Im unclear if the contents of the can counts against the amount of refrigerant I need to fully charge the system. The can of oil includes 8.5oz of oil and 3oz of R-134a. Do I subtract these volumes from amount of R-134 it takes for a full charge ? I know overcharging a system is bad.


#2
Also, I know I have a leak, just not where. I have the leak dye and UV lamp to help me find it, but Im not sure if I should fully charge the system to find the leak, or if just 16oz or so would be enough. I don't want to add refrigerant into a system that I know is going to leak it into the atmosphere, but I'm not sure how else I can locate the leak.

By the way, for those of you in the US Autozone rents AC Vacuum pumps for free.

 

[sfdon]

You charge leaky systems with nitrogen not r134 or r-12
With gauges and a thermometer you shouldn't overcharge at all.
Do your math and watch all 3 gauges.
Only use synthetic oil that is compatible with both gases for obvious reasons.
Car quest carries it.

 

[David]

Thanks for the Nitrogen tip. Looks like the paintball crowd is using nitrogen tanks now, so I should be able to get a small tank locally. I just need to figure out how to regulate it down from 3,000 psi to <100 psi so I dont blow out the AC system.

Still, the capacity recommendation on the car is given in oz, not psi. So my question remains on if the oil charge is an addition to the refrigerant level or a portion of the total charge.

 

[sfdon]

Put in 8 oz.
I like 4 in the receiver and 4 in the compressor.
Run the compressor with a handheld drill first if it's dry.