System Performance Test

Figure 1 A/C System Performance Test Specifications:

When performing air conditioning diagnosis on vehicles equipped with a catalytic converter, warm the engine to a normal operating temperature before attempting to idle the engine for more than five minutes.
1. Open all doors or windows.
2. Turn A/C On (normal mode), temperature control in Cold position and the blower switch in Hi position.
3. Install a J-21213-A four jack-dual range temperature tester at the instrument panel right outlet, then take temperature reading.
4. Start the engine and run at 2000 RPM.
5. After one minute, take temperature reading at the right outlet. The minimum drop in temperature should correspond to Fig. 1.

RELATIVE TEMPERATURE OF HIGH & LOW SIDES
The high side of the system should be uniformly hot to the touch throughout. A difference in temperature will indicate a partial blockage of liquid or gas at this point.
The low side of the system should be uniformly cool to the touch with no excessive sweating of the suction line or low side service valve. Excessive sweating or frosting of the low side service valve usually indicates an expansion valve is allowing an excessive amount of refrigerant into the evaporator.

EVAPORATOR OUTPUT
At this point, provided all other inspection tests have been performed, and components have been found to operate as they should, a rapid cooling down of the interior of the vehicle should result. The use of a thermometer is not necessary to determine evaporator output. Bringing all units to the correct operating specifications will insure that the evaporator performs as intended.