Functional Test

FUNCTIONAL TEST
The following procedure can be used to quickly check whether the A/C system has the proper charge. It can be used only when ambient air temperature is more than 21°C (70°F). This simple check can be made in minutes, quickly determining if the system charge is the problem.

1. The engine must be warm and at normal idle speed.
2. Open the hood and the car doors.
3. Move the mode lever to "NORM."
4. Move the temperature lever to the "FULL COLD" position.
5. Move the blower switch to "HI."
6. With the compressor engaged, touch the evaporator inlet pipe (after the orifice tube) and the surface of the accumulator. Compare the temperatures.
a. At same temperature AND both cooler than ambient air -The system is operating properly. Check for other problems using the Cycling Clutch Orifice Tube Diagnostic Charts. [1][2]Symptom Related Diagnostic Procedures
b. Inlet pipe COOLER than accumulator surface -This indicates a low refrigerant charge. To correct:
^ Add R-12 refrigerant in small amounts (0.12 kg, 0.25 lbs.) until the inlet pipe and the accumulator feel as if they are the same temperature. (After adding refrigerant, allow time for it to stabilize before adding more.)
^ Then, add one more can (0.42 kg, 14 oz.) of R-12 refrigerant. (The 0.42 kg/14 fl. oz. disposable can of R-12 refrigerant is equivalent to 0.88 lb.)
c. Inlet pipe has frost buildup and is cooler than accumulator -Follow the procedure under Step b (above).

NOTE If a malfunction in the refrigerant system is suspected due to abnormal system pressures, check the following:

1. Check the outer surfaces of the radiator and condenser cores to be sure air flow is not blocked by dirt, leaves or other foreign material. Be sure to check between the condenser and radiator as well as the outer surfaces.
2. Check for restrictions in the condenser core.
3. Check for refrigerant leaks.
4. Check all the air ducts for leaks or restrictions. A low air flow rate may indicate a restricted evaporator core.
5. Check for compressor clutch slippage.
6. Check for improper drive belt tension.
7. Check for a plugged accumulator or orifice tube.
8. Check for moisture in the refrigerant system.