Component Tests and General Diagnostics

Fig. 1 Relative Humidity Chart:

Fig. 2 A/C Operation Chart.:

1. Install manifold gauge set.
2. Run engine at 2000 RPM and set controls for maximum cooling and high blower speed.
3. Open all windows and doors.
4. Place dry-bulb thermometer in cool air outlet.
5. Place psychrometer (combination wet and dry-bulb thermometers) close to cooling unit inlet.
6. Ensure reading on high pressure gauge is 199-228 psi. On RX-7 models, pressure should be 149-192 psi.
7. If reading is too high, pour water on condenser and, if reading is too low, cover front of condenser.
8. Ensure reading of dry-bulb thermometer at air inlet is 77-95°F.
9. Calculate relative humidity from psychrometric graph, Fig. 1, by comparing wet and dry-bulb readings of psychrometer.
10. Measure dry-bulb temperature at cool air outlet, then calculate difference between inlet dry-bulb and outlet dry-bulb temperatures.
11. If intersection of relative humidity and temperature difference is between two hatched lines, Fig. 2, cooling performance is satisfactory.