Refrigerant System Tests

Special Tool(s) 

Fig 1: Identifying R-134a Manifold Gauge Set

Courtesy of FORD MOTOR CO.

1. Connect the R-134a Manifold Gauge Set. For additional information, refer to MANIFOLD GAUGE SET CONNECTION .
2. Adjust the climate controls for maximum cooling.
   • Start the engine.
   • Select MAX A/C operation.
   • Set the blower motor speed to maximum.
3. Stabilize the in-vehicle temperature at 21-27°C (70-80°F).
NOTE: When the ambient temperatures exceed 38°C (100°F), do not run the engine above normal idle speed.
Fig 2: Maintaining Engine Speed At 1,500 RPM
Courtesy of FORD MOTOR CO.
4. Maintain the engine speed at 1,500 RPM.
5. Determine the compressor discharge (high) pressure.
   1. Record the ambient temperature.
   2. Record the discharge (high) pressure.
   NOTE: In ambient temperatures between 38-43°C (100-110°F), the system performance pressures will be the same as those for ambient temperatures shown on the chart in the 32-38°C (90-100°F) range.
   Fig 3: Identifying Ambient Temperature Specifications
   Courtesy of FORD MOTOR CO.
   3. The system performance is acceptable when the pressure reading falls between the upper and lower limits shown.
6. Determine the compressor suction (low) pressure.
   1. Record the ambient temperature.
   2. Record the suction (low) pressure.
   NOTE: In ambient temperatures between 38-43°C (100-110°F), the system performance pressures will be the same as those for ambient temperatures shown on the chart in the 32-38°C (90-100°F) range.
   Fig 4: Identifying Ambient Temperature & Suction (Low) Pressure
   Courtesy of FORD MOTOR CO.
   3. The system performance is acceptable when the pressure reading falls between the upper and lower limits shown.
7. Determine the A/C clutch ON time.
   1. Record the ambient temperature.
   2. Record the A/C clutch ON time in seconds.
   NOTE: When the ambient temperature is above 26°C (80°F), the A/C clutch may not cycle.
   Fig 5: Identifying Ambient Temperature Upper & Lower Limits
   Courtesy of FORD MOTOR CO.
   3. The system performance is acceptable when the recorded time falls between the upper and lower limits shown.
8. Determine the A/C clutch OFF time.
   1. Record the ambient temperature.
   2. Record the A/C clutch OFF time in seconds.
   NOTE: When the ambient temperature is above 26°C (80°F), the A/C clutch may not cycle.
   Fig 6: Identifying Ambient Temperature & A/C Clutch Off Time In Seconds
   Courtesy of FORD MOTOR CO.
   3. The system performance is acceptable when the recorded time falls between the upper and lower limits shown.
9. Determine the total A/C clutch cycle time.
   1. Record the ambient temperature.
   2. Record the time the A/C clutch is engaged plus the time it is disengaged (time ON plus time OFF).
   NOTE: When the ambient temperature is above 26°C (80°F), the A/C clutch may not cycle.
   Fig 7: Identifying Ambient Temperature & A/C Clutch Engaged Time ON Plus Time OFF
   Courtesy of FORD MOTOR CO.
   3. The system performance is acceptable when the recorded time falls between the upper and lower limits shown.
10. Determine the A/C clutch cycle rate per minute.
    1. Record the ambient temperature.
    2. Record the number of A/C clutch cycles occurring in one minute.
    NOTE: When the ambient temperature is above 26°C (80°F), the A/C clutch may not cycle.
    Fig 8: Identifying Ambient Temperature & A/C Clutch Cycles Occurring In One Minute
    Courtesy of FORD MOTOR CO.
    3. The system performance is acceptable when the recorded number of cycles falls between the upper and lower limits shown.
11. Determine the center A/C register discharge temperature.
    1. Record the ambient temperature.
    2. Record the center A/C register discharge temperature.
    NOTE: In ambient temperatures between 38-43°C (100-110°F), the A/C register discharge temperatures will be the same as those for ambient temperatures shown on the chart in the 32-38°C (90-100°F) range.
    Fig 9: Identifying Ambient Temperature & A/C Register Discharge Temperature
    Courtesy of FORD MOTOR CO.
    3. The system performance is acceptable when the center A/C register discharge temperature falls between the upper and lower limits shown.