My questions concern the compressor oil that is within the system.

1. If one slowly loses R-134a due to a slow leak, is one also losing a proportionate amount of the compressor oil ??

2. Instead of just adding a can of plain refrigerant, should the kind that includes oil be used instead ??


3. Looking at this from a different angle, if a component is replaced, such as the drier/accumulator, or maybe a hose, and the system is then pulled under vacuum for a few hours, is ALL the compressor oil also lost, or does it remain in the system ??


Thanks.

 

I hope this explains everything for you.
Oil loss may occur due to component replacement, or a rupture or leak from a refrigerant line, connector fitting, component or component seal. If a leak occurs, add 30 milliliters (1 fluid ounce) of the recommended refrigerant oil to the refrigerant system after the repair has been made. Refrigerant oil loss will be evident at the leak point by the presence of a wet, shiny surface around the leak.
When an air conditioning system is first assembled at the factory, all components (except the A/C compressor) are refrigerant oil free. After the refrigerant system has been charged with (R-134a) refrigerant and operated, the oil in the A/C compressor is dispersed through the lines and components. The A/C evaporator, A/C condenser, and accumulator will retain a significant amount of oil. Refer to the A/C Component Refrigerant Oil Capacities table. When a component is replaced, the specified amount of refrigerant oil must be added. When a new A/C compressor is being installed, drain the lubricant from the used compressor, measure the amount drained and discard the used lubricant. Drain the lubricant from the new A/C compressor into a clean container. Return the amount of lubricant measured from the used compressor, plus the amount reclaimed from the system back into the new A/C compressor. When a line or component has ruptured and oil has escaped, the accumulator must be replaced along with the ruptured component.

A/C COMPONENT REFRIGERANT OIL CAPACITIES Component ml. oz.
Total System Fill 180 6
Accumulator 60 2
Condenser 30 1
Evaporator 60 2
Compressor Drain and measure the oil from the old compressor - see text.

 

Thank you.

That clears up some of my questions.

 

Your post said a slow leak so I would not add much if any oil after your repair if you replaced a hose, o'ring or gasket.

You would want to add oil if one of the larger capacity items were replaced. Too much oil can/will hamper the systems ability to cool properly.