A/C Performance Testing

A/C Performance Temperature Chart:

OPERATION
The air conditioning system is designed to remove heat and humidity from the air entering the passenger compartment. The evaporator, located in the heater A/C unit, is cooled to temperatures near the freezing point. As warm damp air passes over the fins in the evaporator, moisture in the air condenses to water, dehumidifying the air. Condensation on the evaporator fins reduces the evaporators ability to absorb heat. During periods of high heat and humidity, an air conditioning system will be less effective. As the passenger compartment air dehumidifies, A/C performance levels rise.

WARNING: Review Safety Precautions and Warnings before proceeding with this procedure.

NOTES:
- When connecting the service equipment coupling to the line fitting, verify that the valve of the coupling is fully closed. This will reduce the amount of effort required to make the connection.
- Air temperature in test room and on vehicle must be 21°C (70°F) minimum for this test.

PERFORMANCE TEST PROCEDURE
1. Connect a tachometer and manifold gauge set. Attach a thermocouple to the evaporator line.
2. Set control to A/C, temperature lever on full cool and blower on high.
3. Start engine and hold at 1,000 rpm with A/C clutch engaged.
4. Engine should be warmed up.

NOTE: Verify water valve is in the closed position. Check both heater hoses at cowl, past the water valve. The hoses should be cool to the touch. To verify the valve is functioning, remove cable at the valve. Open the water valve. Check temperature of hoses. Hose temperature should increase instantly.

5. Insert a thermometer in the A/C outlet and operate the engine for five minutes. The A/C clutch may cycle depending on ambient conditions.
6. With the A/C clutch engaged, compare the discharge air temperature to the A/C Performance Temperature Chart.
7. If the discharge air temperature fails to meet the specifications. Refer to the System Charge Level.