Mazda MX-3 silhouetteMX-3

AIR CONDITIONER — Performance Test

G-52prose procedure

REC/FRESH and mode controls differ between wire type and logic type A/C control panels.

Performance Test

After servicing the refrigerant system, test its performance.

Performance Test

  1. 1
    Install the manifold gauge set. (Refer to page G-50.)
  2. 2
    Place a dry-bulb thermometer in the center ventilator outlet.
    Instrument-panel interior view showing placement of a dry-bulb thermometer in the center ventilator outlet and a wet-and-dry-bulb thermometer at the blower inlet (in the footwell area).
  3. 3
    Place a wet-and-dry-bulb thermometer at the blower inlet.
  4. 4
    Open all doors and windows.
  5. 5
    Warm up the engine and run it at constant 1,500 rpm.
  6. 6
    Set the fan switch at the fourth position.
  7. 7
    Turn the A/C switch on.
  8. 8
    Set the REC/FRESH lever (wire type) or REC/FRESH switch (logic type) at recirculate.
  9. 9
    Set the mode lever (wire type) or mode switch (logic type) to VENT.
  10. 10
    Set the temperature control lever to MAX COLD.
  11. 11
    Wait until the air conditioner output temperature stabilizes.
    Stabilized condition — Blower inlet temperature: 25-35 degC {77-95 degF}; High-pressure-side reading: 1380-1660 kPa {14.0-17.0 kgf/cm2, 200-241 psi}
  12. 12
    After the air conditioner stabilizes, read the wet-and-dry-bulb thermometer, and then calculate the relative humidity by using the graph below.
    Psychrometric chart for determining relative humidity from wet-bulb and dry-bulb temperatures. X-axis is dry-bulb temperature (degC), curved lines are wet-bulb temperature and relative humidity (%), with an EXAMPLE dotted-line intersection marked. Includes a 'HOW TO READ THE GRAPH' instruction block: after measuring wet- and dry-bulb temperatures at the evaporator air inlet, relative humidity (%) can be obtained. Example: supposing dry- and wet-bulb temperatures at evaporator air inlet are 25 degC and 19.5 degC respectively, the point of intersection of the dotted lines in the graph is 60%.
  13. 13
    Read the dry thermometer at the air outlet, and calculate the difference between the inlet dry-bulb and outlet dry-bulb temperatures.
    Graph of temperature difference between inlet and outlet (Y-axis, degC/degF: 10/50, 15/59, 20/68) versus relative humidity (X-axis, %: 50, 60, 70). Two curves bound a shaded acceptable zone for verifying performance.
  14. 14
    Verify that the intersection of the relative humidity and temperature difference is in the shaded zone.
Blower inlet temperature
25-35degC {77-95 degF}
High-pressure-side reading
1380-1660kPa {14.0-17.0 kgf/cm2, 200-241 psi}
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See also

page G-50

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