Pressure, Vacuum and Temperature Specifications

Performance testing provides a measure of air conditioning system operating efficiency by measuring and comparing pressures at the high-pressure and low-pressure sides of the refrigeration system and the temperature of the air being discharged into the passenger compartment.

The high-pressure gage of J 23575-01 or equivalent should be connected to the high-pressure side service fitting using J 38702 or equivalent and the low-pressure gage of J 23575-01 or equivalent should be connected to the low-pressure side service fitting. Both gage valves must be closed while making the connections. The center hose fitting J 23575-01 also must be closed, and must remain closed during the performance test.

The hood should be open and all doors and window should be closed during the test. The heater and air conditioning control assembly must be set for 16°C (60°F), "AUTO" mode and high blower motor speed.

A high volume fan should be placed in front of the radiator grille to insure an adequate supply of airflow across the condenser assembly. After idling the engine for ten minutes, the engine speed should be increased to 2000 rpm for the test.

Pressure / Temperature Relationship Of R-12:

Just before making the Performance Test, the temperature and relative humidity of the ambient air (the air being blown against the condenser assembly) should be determined. Then the temperature of the air being discharged from a center instrument panel outlet should be measured with J 6742-03 or equivalent and the low-pressure gage and high-pressure gage of J 23575-01 should be read. Record the readings and compare them to the data shown in the chart.

If operating temperatures and pressures are within the normal range, the refrigeration system can be considered to be operating properly. Slight variations from the published readings can be considered acceptable if experience has shown that such minor deviations do not indicate a problem.