Refrigeration System Performance Test

System performance check should be performed as both initial diagnostic check for cooling related complaints and final check after repairs are completed.
1. Connect manifold gauge set to A/C system and place temperature sensors at evaporator outlet and outside vehicle.
2. Start engine and run until it reaches normal operating temperature. Front of vehicle should be at least 5 ft. away from any wall or air obstruction during test. Use an external fan to force air past condenser, if necessary.
3. Place blower switch (A/C blower switch, if equipped) in high position and A/C control in maximum cooling position.
4. A/C compressor clutch should engage. If clutch does not engage, check clutch and electrical circuit.
5. Close doors windows and vents, then set engine to run at 2000 RPM:

Fig. 1 Sight Glass Inspection Procedure Chart:

a. Perform sight glass inspection, Fig. 1.
b. Observe compressor clutch operation. Clutch should cycle off and on as evaporator.

Fig. 2 Performance Specification Chart:

c. After approximately 15 minutes, note gauge reading with compressor clutch engaged. Reading should be within 15% of specifications, Fig. 2.

Fig. 3 Refrigeration System Analysis Chart:

Fig. 4 Insufficient Cooling Diagnosis Chart (Part 1 Of 2). Note: TX Valve-expansion Valve; Thermostatic Switch Not Adjustable On All Models:

Fig. 4 Insufficient Cooling Diagnosis Chart (Part 2 Of 2). Note: TX Valve-expansion Valve; Thermostatic Switch Not Adjustable On All Models:

d. If reading are not as specified or evaporator outlet temperature is not within specified range, refer to diagnostic charts, Figs 3 and 4.