Refrigerant Oil Addition

When replacing components of the air conditioning refrigerant system, measured quantities of oil should be added to the replacement components. The refrigerant oil required for R-134a systems is a Polyalkylene Glycol (PAG) oil meeting Ford specification WSH-M1C231-B. It is important that only the specified type and quantity of refrigerant oil be used. A surplus of oil will reduce the cooling capacity of the system. Too little oil will result in poor lubrication of the A/C compressor.

R-134a Refrigerant Oil

CAUTION: Do not add R-134a refrigerant oil to an R-12 system. Also, do not add R-12 refrigerant oil to an R-134a system. Mixing these two types of refrigerant oils may cause poor lubricant circulation resulting in component failure and damage to the A/C systems.

The refrigerant oil required for R-134a A/C systems is a Polyalkylene Glycol (PAG) oil meeting Ford specification WSH-M1C231-B. This type of Motorcraft refrigerant oil YN-12b was made specifically for R-134a systems and is not suitable for use in R-12 systems. Never use an R-134a refrigerant oil in R-12 systems.

R-12 systems require the use of a mineral based refrigerant oil with special additives known as YN-9. This type of refrigerant oil was made specifically for R-12 systems and is not suitable for use in R-134a systems. Never use R-12 refrigerant oil YN-9 in R-134a systems.

During Component Replacement
If a refrigerant system component is removed after the system has been operated, some oil will go with it. To maintain the original oil charge, it is necessary to compensate for the amount of oil lost with the old component by adding an equal amount to the new component. Clean refrigerant oil should be added to the replacement components as follows:
^ A/C evaporator core - Add 90 ml (3 oz)
^ A/C condenser core - Add 30 ml (1 oz)
^ Suction accumulator/drier - Drain the oil from the old suction accumulator/drier. Add the same amount plus 60 ml (2 oz) of clean refrigerant oil to the new suction accumulator/drier.

Pour the clean refrigerant oil directly into the replacement component.

Other Refrigerant System Components
If any other components such as the A/C evaporator core orifice or a refrigerant line are replaced, no additional refrigerant oil is necessary.