A/C COMPRESSOR DRIVE BELT TENSION CHECK AND ADJUSTMENT


Check the drive belt tension by the following procedures.

STANDARD VALUE:
Item
 When checked
 When adjusted
 When replaced
Vibration frequency Hz
 222.5 - 251.0
 222.5 - 251.0
 259.8 - 300.0
Tension N
 363 - 462
 363 - 462
 495 - 660
Deflection mm (Reference)
 6.8 - 8.0
 6.8 - 8.0
 5.1 - 6.4

<WHEN THE VIBRATION FREQUENCY IS MEASURED {SPECIAL TOOL (MB992080) IS USED}: RECOMMENDATION>
note The vibration frequency measuring method is recommended for check and adjustment of the drive belt tension.

1.Connect the Special tool microphone assembly (MB992082) to the Special tool belt tension meter (MB992081) of the Special tool belt tension meter set (MB992080).
2.Press the "POWER" button to turn on the power supply.
3.Press the numeral key of "1" and check that "No.1" appears on the upper left of the display.
note This operation is to temporarily set the preset data such as the belt specifications, because if the measurement is taken without input of the belt specifications, conversion to tension value (N) cannot be made, resulting in judgement of error.
4.Press "Hz" button twice to change the display to the frequency display (Hz).

5.
caution
  • The temperature of the surface of the belt should be as close as possible to normal temperature.
  • Do not let any contaminants such as water or oil get onto the microphone.
  • If strong gusts of wind blow against the microphone or if there is loud sources of noise nearby, the values measured by the microphone may not correspond to actual values.
  • If the microphone is touching the belt while the measurement is being made, the values measured by the microphone may not correspond to actual values.
  • Do not take the measurement while the vehicle’s engine is running.
Hold the microphone to the middle of the drive belt between the pulleys (at the place indicated by the arrow), about 10 - 15 mm away from the rear surface of the belt and so that it is perpendicular to the belt (within an angle of ± 15 °).
6.Press the "MEASURE" button.
7.Gently tap the middle of the belt between the pulleys (the place indicated by the arrow) with your finger as shown in the illustration, and check that the vibration frequency of the belt is within the standard value.
note To take the measurement repeatedly, fillip the belt again.
8.After the completion of the measurement, press and hold the "POWER" button to turn off the power supply.

<WHEN THE VIBRATION FREQUENCY IS MEASURED VEHICLE COMMUNICATION INTERFACE (V.C.I.) IS USED: RECOMMENDATION>
note The vibration frequency measuring method is recommended for check and adjustment of the drive belt tension.


1.
caution To prevent damage to special tool V.C.I. (MB991824), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting special tool V.C.I. (MB991824).
Connect special tool belt tension meter set (MB991668) to special tool V.C.I. (MB991824).
2.Connect special tool M.U.T.-III main harness A (MB991910) to special tool V.C.I. (MB991824).
3.Connect special tool M.U.T.-III main harness A (MB991910) to the diagnosis connector.
4.Turn the ignition switch to the "ON" position and select "Belt Tension Measurement" from the menu screen.

5.
caution
  • The temperature of the surface of the belt should be as close as possible to normal temperature.
  • Do not let any contaminants such as water or oil get onto the microphone.
  • If strong gusts of wind blow against the microphone or if there is loud sources of noise nearby, the values measured by the microphone may not correspond to actual values.
  • If the microphone is touching the belt while the measurement is being made, the values measured by the microphone may not correspond to actual values.
  • Do not take the measurement while the vehicle’s engine is running.
Hold the microphone to the middle of the drive belt between the pulleys (at the place indicated by the arrow), about 10 - 20 mm away from the rear surface of the belt and so that it is perpendicular to the belt (within an angle of ± 15 °).
6.Gently tap the middle of the belt between the pulleys (the place indicated by the arrow) with your finger as shown in the illustration, and check that the vibration frequency of the belt is within the standard value.

<WHEN USING THE TENSION GAUGE>

Place a belt tension gauge at the centre of the belt between the pulleys, and check that the belt tension is within the standard value.

<BELT DEFLECTION CHECK>

Apply approximately 100 N of pressure against the location between the pulleys shown by the arrow in the illustration and then measure the deflection.
When the belt tension is adjusted by measuring the belt deflection, adjust it with a tool for vibration frequency measurement or tension measurement afterward.
If not within the standard value, adjust the belt tension by the following procedure.

1.Loosen the locking nut of the tensioner pulley.
2.Use the adjusting bolt to adjust the belt tension. The tension will increase when turning the adjusting bolt clockwise, and decrease when turning anti-clockwise.
3.Tighten the locking nut.
4.Tighten the adjusting bolt.
5.
caution When checking the belt tension, turn the crankshaft clockwise one turn or more.
Check the belt tension, and readjust if necessary.