Discharging A/C System

Before replacing any air conditioning component, the system must be completely discharged of Refrigerant-12. ALWAYS DISCHARGE THE SYSTEM AT THE LOW-SIDE SERVICE FITTING.

1. With the ignition "OFF," remove the protective cap from the Schrader valve fitting on the low-side line, located on the left side of the engine compartment (the line runs between the evaporator and the compressor). Connect manifold gage set using hose adapters. Place center discharge hose into an oil bottle or bucket to catch compressor oil. Slowly open valve on manifold set and the R-12 will begin to escape into the container. If no discharge occurs, check for a missing or faulty Schrader valve depressor or hose fitting.
2. With the low-side of the system fully discharged, check the high-side system fitting for any remaining pressure.
3. If pressure is found, attempt to discharge the high-side using the same procedure as for the low-side. Pressure on this side indicates a high-side restriction. The cause must be diagnosed and corrected before evacuating and charging the system.
4. When the system is completely discharged, measure and record the amount of refrigerant oil in the container. This amount of new oil will have to be added to the system prior to recharging.

NOTICE: If the system is discharged slowly enough, it is possible that little or no A/C oil will escape. Follow the proceding procedures so that you can tell if any A/C oil was lost during discharge, and so you know how much you may need to add before charging.