Insufficient Cooling Quick Check

If outside air temperature is above 21°C (70°F), the following procedure can be used to quickly determine whether the air conditioning refrigeration system has the proper charge of Refrigerant-12. This check can be made in a few minutes, simplifying system diagnosis by localizing the problem to a low refrigerant charge or eliminating that possibility.

NOTE: The first step in AC diagnosis is to perform the Electronic Climate Control (ECC) System Check.

The engine must be at normal operating temperature and running at normal idle speed. The hood and all body doors must be open. The heater and air conditioning control assembly must be set for maximum air conditioning, high blower motor speed and full cool temperature setting.

When the compressor assembly is operating, the technician should use a hand to feel the temperature of the evaporator inlet tube downstream from the expansion tube. Then the technician should feel the surface of the accumulator assembly.

The technician should compare and evaluate the temperatures of the two components. Proper operation with an adequate refrigerant charge is indicated if both the evaporator inlet tube and the accumulator assembly feel cooler than the outside air and both seem to be at the same temperature.

If the evaporator inlet tube is cooler than the accumulator assembly, or if the inlet has a coating of frost, a low refrigerant charge is indicated.