[Tom Pugh]

I have a newly rebuilt A6 ac system (engine compartment side) in my '67 GTO. I have 60 oz. of R12 and a case (24 cans) of oil which are labeled ' 2oz R12/2oz oil '. (maybe these are just for topping off a system?) Anyway, Not sure how much oil the system takes. Can I punch these cans and add it directly in to the compressor or is there a better way to add the R12/oil mix?

[TacoTownCharlie]

I'm working on my R12 system right now so I might be able to help. The amount of oil to add can be a mystery; you have to estimate how much oil is already in the system. Is everything new, condenser, compressor, evaporator and receiver/dryer? If those weren't replaced and were in good working condition (no leaks) then they will have some oil still in them.

If everything is new then you need to check the compressor, it's not uncommon for new or rebuilt units to ship with 8oz of oil in it. If it has oil you need to make sure it is compatible with R12 (PEG or Mineral oil but not PAG oil). I had to drain my new compressor of the PAG oil it shipped with and refilled with Mineral oil.

For my 1978 Trans AM the total oil for an R12 system is 10oz. It looks like 3oz is in the Evaporator, 1oz is in the Condenser and the rest is in the compressor sump. The receiver/dryer usually holds onto 1oz.

Hopefully, someone will have the 67 GTO specs.

Is your system sealed? Is it under vacuum or is it pressurized? If it is sealed but no pressure (no R12 in the system) then you can detach the hoses to the compressor and fill the system from the drain valve. This valve on the A6 is in the middle of the body and clocked to the bottom when mounted.

If it is a pressurized system you'll need to recover the R12 that's in there before you can open the system.

Hope this helps get you started. I'm sure other people will have suggestions and questions. This R12 setup was used for decades and serviced by thousands of people. With a little help I'm sure you will have a a great system.

TacoTownCharlie

[Formula403]

A vacuum test will remove any residue and debris and locate any leaks, so you can start from scratch with amount required by compressor sump and system. Compressor decal has details, if original, as does Service Manual.

[gto4ben]

For '67 GTO (and other intermediates), the amount of oil replaced per component is in this chart. If you bought a new or rebuilt compressor, they usually are prefilled with oil and you'll need to drain an amount equivalent to the component that isn't replaced. In addition, confirm the type of oil used in the new/rebuilt compressor (mineral or PAG) so you aren't mixing different types.

I prefer to add oil directly instead of the R12/mineral oil cans but it can be done. I believe you need to invert the cans to insure the R12 pressure pushes the oil into the system. Have a 5 gallon bucket filled with hot water from the tap standing by (not boiling!). Refrigerant in the cans will lower the temperature of the can. Immersing it to warm it up will insure all the refrigerant possible will be placed in the system. An alternate method is to weigh it using a scale before and after.

Number one advice I can offer is replace the receiver dryer every time you open up the system. The desiccant doesn't hold a lot of moisture so you need a fresh one.