Performance Test

Fig. 4 Air Conditioning System Performance Chart:

A/C cooling performance changes considerably with changes in surrounding conditions. To check for correct system operation, follow this procedure:

1. Park vehicle indoors or in shade.
2. Open all windows and keep doors closed.
3. Connect manifold gauge set to system service valves.
4. Set mode switch to A/C MAX position, then air inlet control switch to CIRC.
5. Set temperature lever to COLD position.
6. Start engine and hold speed at 1500 rpm.
7. After A/C has been operating for 10 minutes, measure system pressures.
8. Measure temperatures of inlet air to blower and outlet air at dash panel grilles.
9. Measure temperature and humidity of ambient air at a point 3.3 feet from front of condenser.
10. Check for abnormalities by comparing test results with standard pressure in performance charts Fig. 4.
11. Pressure will change in the following manner with changes in conditions:
a. When blower speed is low, discharge pressure will drop.
b. When humidity of intake air is low, discharge pressure will drop.
12. Temperature will change in the following manner with changes in conditions:
a. When ambient air temperature is low, outlet air temperature will become low.