[OilPan]

Now that summer is over, I am ready to evacuate and charge the factory AC system in my 67 GTO. We have a new replacement condenser, new drier from Ames, new txv, adjusted POA valve, and new barrier hoses. We flushed the evaporator. The new compressor is from Four Seasons. The generic instructions they provided state that it is charged with 3 oz of oil. It then states "must add recommended amount and type". We are converting to r134.

Can someone tell me what the oil, and r12 freon capacity is for this car. My service manual is on CD and hard to access. thanks.

[Blued and Painted]

Oil for 134 and r12 are not compatible. I believe PAIG oil is what you are looking for. If the system is open, i like to pore and ounce or more in each large component. Dryer, evaporator, condenser, and compressor. Then evacuate and charge. If the system is sealed up, pull into a vacuum and suck oil into system.
It should take 3 or 4, 12 oz cans of 134 to charge the system. Gauge readings at 1500 rpm's with fan in front of vehicle -- low side 29 to 35psi,,, High side 200 to 250 psi. Stop adding freon when these readings are reached. More freon will not make it cooler. Charging and a/c system without gauges is like reading in darkness. Diagnostics is impossible without gauge readings.

IIRC, Ester oil can be used with both types of freon. Read the container.

[OilPan]

Thanks for the info. I am worried about adding too much or too little oil. I have an old Haynes manual that states GM system capacity with the A6 compressor is 10 oz. The Four Seasons instructions states: "the only moving component in the system is the compressor". Okay, then why do we need oil everywhere else? Because it goes into solution with the freon and doesn't stay put? Then perhaps 10 oz is the saturation level?

[OilPan]

Starting to answer my own questions here. I found a compressor tag online for 64-69 that shows 3.75 lb R12 refrigerant for the Tempest and 4.12 lb for the large Pontiac.
I plan to charge to 80% of 3.75lb for the R134.

But I am still unsure about the oil. It seems the A6 has a 10 oz sump capacity. Classic Auto Air states that their "rebuilds come with a full system charge". And that "It’s typically ok for an extra ounce or two of oil to remain in the system" A significant overcharge of oil (over 2 ounces) however, can cause multiple problems. So perhaps I don't need to add more than ounce or two, and the 10oz is only for an A6?