A/C Refrigerant System Tests: Notes

Connect the manifold gauge set.
Adjust the climate control for maximum cooling.
1. Start the engine.
2. Select MAX A/C operation.
3. Set the blower motor speed to maximum.
Stabilize the in-vehicle temperature at 21°C-27°C (70°F-80°F).
NOTE:
- When the ambient temperatures exceed 38°C (100°F), do not run the engine above normal idle speed.
Maintain the engine speed at 1500 RPM.
Determine the compressor discharge (high) pressure.
1. Record the ambient temperature.
2. Record the discharge (high) pressure.
  NOTE:
  - In ambient temperatures between 38°C-43°C (100°F-110°F), the system performance pressures will be the same as those for ambient temperatures shown on the chart in the 32°C-38°C (90°F-100°F) range.
3. The system performance is acceptable when the pressure reading falls between the upper and lower limits as shown in the illustration.
Fig 1: Upper And Lower Pressure Limit Reference Graph (1 Of 2)
Courtesy of MAZDA MOTORS CORP.
Determine the compressor suction (low) pressure.
1. Record the ambient temperature.
2. Record the suction (low) pressure.
  NOTE:
  - In ambient temperatures between 38°C-43°C (100°F-110°F), the system performance pressures will be the same as those for ambient temperatures shown on the chart in the 32°C-38°C (90°F-100°F) range.
3. The system performance is acceptable when the pressure reading falls between the upper and lower limits as shown in the illustration.
Fig 2: Upper And Lower Pressure Limit Reference Graph (2 Of 2)
Courtesy of MAZDA MOTORS CORP.
Determine the A/C clutch ON time.
1. Record the ambient temperature.
2. Record the A/C clutch ON time (for one cycle) in seconds.
  NOTE:
  - When the ambient temperature is above 26°C (80°F), the A/C clutch may not cycle.
3. The system performance is acceptable when the recorded time falls between the upper and lower limits as shown in the illustration.
Fig 3: Upper And Lower Time Limit Reference Graph (1 Of 3)
Courtesy of MAZDA MOTORS CORP.
Determine the A/C clutch OFF time.
1. Record the ambient temperature.
2. Record the A/C clutch OFF time (for one cycle) in seconds.
  NOTE:
  - When the ambient temperature is above 26°C (80°F), the A/C clutch may not cycle.
3. The system performance is acceptable when the recorded time falls between the upper and lower limits as shown in the illustration.
Fig 4: Upper And Lower Time Limit Reference Graph (2 Of 3)
Courtesy of MAZDA MOTORS CORP.
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) for one cycle.
  NOTE:
  - When the ambient temperature is above 26°C (80°F), the A/C clutch may not cycle.
3. The system performance is acceptable when the recorded time falls between the upper and lower limits as shown in the illustration.
Fig 5: Upper And Lower Time Limit Reference Graph (3 Of 3)
Courtesy of MAZDA MOTORS CORP.
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:
  - During A/C operation, the A/C clutch will cycle ON (engaged) and OFF (disengaged). When the ambient temperature is above 26°C (80°F), the A/C clutch may not cycle.
3. The system performance is acceptable when the recorded number of cycles fall between the upper and lower limits shown.
Fig 6: Graph Showing Upper And Lower Limit Of No. Of Record Cycles
Courtesy of MAZDA MOTORS CORP.
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°C-43°C (100°F-110°F), the A/C register discharge temperatures will be the same as those for ambient temperatures shown on the chart in the 32°C-38°C (90°F-100°F) range.
3. The system performance is acceptable when the center A/C register discharge temperature falls between the upper and lower limits shown.
Fig 7: Upper And Lower Temperature Limit Reference Graph
Courtesy of MAZDA MOTORS CORP.