Initial Inspection
ON-VEHICLE INSPECTION1. Air conditioner function check
a. Install the air conditioner tool set.
b. Set the vehicle to the conditions shown [*1].
HINT:
- *2 Since the correct judgement can be done only when the inlet air temperature stays between 25°C (77.0°F) and 35°C (95.0°F), postpone the test if the temperature is not as specified.
- *3 When the condenser pressure (high pressure side gauge) is higher than 1.5 Mpa (15.5 kgf/sq.cm), operate the dial of the gauge manifold to decrease pressure. When the condenser pressure is too low, operate the dial of the gauge manifold to increase pressure.
c. Place dry and wet bulb thermometers at the air inlet opening and insert a dry bulb thermometer at the center of the air outlet opening.
d. Operate the air conditioner with the vehicle in condition [*1] and stabilize the air outlet opening temperature (approx. 5 to 6 minutes).
e. Measure the dry and wet bulb temperature at the air inlet opening and the dry bulb temperature at the air outlet opening.
f. Using the psychrometric chart provided, determine the relative humidity value, based on the measured values of the wet and dry bulb thermometers at the air inlet opening.
1. For example, when the dry-bulb temperature is 25°C (77.0°F) and the wet-bulb temperature is 19.5°C (67.1°F), the relative humidity value is 60%, which is shown in the psychrometric chart as the point where the 2 dotted lines intersect.
g. Using the standard performance chart provided, find the point where the difference between the temperatures measured in the inlet and outlet and the relative humidity intersect.
Standard: The intersecting point is within the shaded area shown in the chart.
1. For example, when the difference between temperatures measured in the inlet and outlet is 17°C (62.6°F) and the relative humidity is 60%, the intersecting point is within the diagonal range. Therefore this air conditioner is normal.
2. INSPECT PRESSURE SWITCH (FOR MAGNET CLUTCH CONTROL)
HINT:
- The switch on the low pressure side detects a drop in refrigerant pressure, such as from refrigerant leakage, etc. and turns the magnet clutch off (*1) to prevent damage to the compressor.
- The switch on the high pressure side detects abnormally high pressure in the air conditioning cycle and turns the magnet clutch off (*1) to prevent damage to parts in the air conditioning cycle.
(*1): The ECM turns the magnet clutch on or off upon receiving the signal from the pressure switch.
- As the pressure switch operates when there is a malfunction with the refrigerant pressure, its function cannot be inspected on-vehicle. Follow the procedures below to inspect it.
a. Inspect refrigerant pressure in air conditioning cycle.
b. Read the manifold gauge pressure when these conditions are established.
Test conditions:
- Temperature at the air inlet with the switch set at RECIRC is 30 to 35°C (86 to 95°F)
- Engine running at 1,500 rpm
- Blower speed control switch at "HI" position
- Temperature control dial at "COOL" position
- Air conditioning switch ON
- Doors open fully
Standard: Pressure on high pressure side:
1.37 to 1.57 MPa (13.9 to 16.0 kgf.sq.cm, 198 to 228 psi)
HINT:
- If the refrigerant pressure is not within the standard range, inspect and repair the air conditioning cycle.
- Proceed to step (b) if the refrigerant pressure is within the specified range.
- If the refrigerant pressure is below 196 KPa (2.0 kgf.sq.cm, 28 psi), the refrigerant amount in the air conditioning cycle may have decreased significantly for reasons such as gas leakage.
c. Check air conditioning operation.
1. Disconnect the pressure switch connector.
2. Connect terminals 1 and 4 of the connector of the pressure switch on the vehicle wire harness side using a service wire.
3. Start the engine.
4. Turn the air conditioning switch on and check that the magnet clutch is turned on.
5. Check that the magnet clutch is turned off when disconnecting terminals 1 and 4 (that are connected in the prior step).
Standard:
Terminals 1 and 4 are connected: magnet clutch is on
Terminals 1 and 4 are disconnected: magnet clutch is off
Replace the pressure switch if the magnet clutch is operated normally.
Inspect and repair the wire harness between the pressure switch and the ECM.
3. INSPECT PRESSURE SWITCH (FOR COOLING FAN CONTROL)
HINT: The switch turns the condenser fan on or off in accordance with pressure in the cycle so that heat exchange in the condenser can be performed effectively within the normal pressure range.
a. Set the manifold gauge.
b. Disconnect the pressure switch connector and connect terminals 1 and 4 using a tool such as a service wire.
c. Connect the positive (+) lead from the ohmmeter to terminal 2 and the negative (-) lead to terminal 3.
d. Start the engine and turn the air conditioning switch on.
e. Check that the continuity between terminals 2 and 3 changes in accordance with the refrigerant pressure as shown in the illustration on the left.
If the operation is not as specified, replace the pressure switch.
4. INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY
a. Disconnect the connector from the air conditioning amplifier assembly and inspect the connector on the wire harness side, as shown in the table.
If the results are not as specified, inspect the circuits connected to the other parts.
b. Connect the connector to the air conditioning amplifier assembly and inspect the wire harness side connector from the back side, as shown in the table.
1. Wave Form 1:
Measure the wave form between terminals C4-13 (BLC) and A4-9 (GND).
OK: A wave form should be output as shown in the illustration.
HINT: Wave form cycle varies with the blower level.
2. Wave Form 2:
Measure the wave form between terminals C4-14 (SPD) and the C4-9 (GND) when turning the rear wheel slowly.
OK: A wave form should be output as shown in the illustration.
HINT: As vehicle speed increases, the cycle of the signal wave form narrows.