A/C Performance Test
A/C SYSTEM TESTINGThe 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. With the control module set to RECIRC, only air from the passenger compartment passes through the evaporator. As the passenger compartment air dehu-midifies, A/C performance levels rise.
PERFORMANCE
Review all Warnings before proceeding with this procedure. Air temperature in test room and on vehicle must be 21 °C (70 °F) minimum for this test.
NOTE: 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.
1. Connect a tachometer and manifold gauge set. Attach a thermocouple to the evaporator outlet line.
2. Set control to A/C, RECIRC, and PANEL, temperature lever on full cool and blower on high.
3. Start engine and hold at 1000 rpm with A/C clutch engaged.
4. Engine should be warmed up with doors and windows closed.
5. Insert a thermometer or place a thermocouple in the left center 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 evaporator inlet line temperature. The evaporator outlet line temperature should be at least 5.5 °C (10 °F) cooler than the discharge air temperature.
7. If the discharge air temperature fails to meet the specifications, refer to the Refrigerant System Leak Test.
REFRIGERANT SYSTEM LEAK
If A/C system is not cooling properly, determine if refrigerant system is fully charged with R-134a. This is accomplished by performing a system Performance Test. If while performing this test A/C liquid line pressure is less than 345 kPa (50 psi) proceed to Refrigerant System Empty. If liquid line pressure is greater than 345 kPa (50 psi) proceed to Refrigerant System Low. If refrigerant system is empty or low a leak at a line fitting or component seal is likely. Check the fittings, lines and components for oily residue, this is an indication of a leak.
REFRIGERANT SYSTEM EMPTY
1. Evacuate the refrigerant system to the lowest degree of vacuum possible (approx. 28 in Hg.). Determine if the system holds a vacuum for 15 minutes. If vacuum is held, a leak is probably not present. If system will not maintain vacuum level, proceed with this procedure.
2. Prepare a 0.284 Kg. (10 oz.) refrigerant charge to be injected into the system.
3. Connect and dispense 0.284 Kg. (10 oz.) of refrigerant into the evacuated refrigerant system.
4. Proceed to the Low Refrigerant Level Leak Test.
REFRIGERANT SYSTEM LOW
1. Determine if there is any R-134a refrigerant in the system.
2. Position the vehicle in a wind free work area. This will aid in detecting small leaks.
3. Bring the refrigerant system up to operating temperature and pressure. This is done by allowing the engine to run for five minutes with the system set to the following:
- Transaxle in Park
- Engine Idling at 700 rpm
- A/C Controls Set in 100 percent outside air
- Blower switch in the high A/C position
- A/C in the ON position
- Open all windows
CAUTION: Leak detectors designed for R-12 refrigerant (only) will not detect leaks in a R-134a refrigerant system.
4. Shut off the vehicle and wait 2 - 7 minutes. Then use an Electronic Leak Detector that is designed to detect R-134a type refrigerant and search for leaks. Fittings, lines, or components that appear to be oily usually indicates a refrigerant leak. To inspect the evaporator core for leaks, insert the leak detector probe into the drain tube opening or a heat duct.
NOTE: A R-134a dye is available to aid in leak detection. Use only DaimlerChrysler (Mopar) approved refrigerant dye.
If a thorough leak check has been completed without indication of a leak, proceed to System Charge Level.