Initial Inspection and Diagnostic Overview

Fig. 3 A/C Performance Chart. 1989-91 Civic:

Fig. 4 A/C Performance Chart. 1992 Civic:

1. Connect gauge set to A/C system.
2. Insert a thermometer in the vent outlet, then determine relative humidity and ambient air temperature.
3. Test conditions should be as follows:
a. Avoid direct sunlight.
b. Open engine hood.
c. Set temperature control dial to max and push vent and fresh air buttons.
d. Turn fan switch to max.
e. Run engine at 1,500 RPM with no driver or passengers in vehicle.
4. After running air conditioner for 10 minutes, read delivery temperature from thermometer in dash vent and pressure readings from both high and low side gauges.
5. Complete charts in Figs. 3 and 4 as follows:
a. Mark delivery temperature along the vertical line.
b. Mark intake temperature (ambient air temperature) along the bottom line.
c. Draw a line straight up from air temperature to humidity level.
d. Mark a point one line above and one line below humidity level, then from each point, draw a horizontal line across to the delivery temperature.
e. Delivery temperature should fall between the two lines.
f. Complete low and high side pressure test in the same manner.
g. Any measurements outside the line may indicate a need for further inspection and/or repair.