NO.17 COOLING SYSTEM CONCERNS-OVERHEATING[LF, L3]
id0103b2802300
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17 |
COOLING SYSTEM CONCERNS -OVERHEATING |
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DESCRIPTION
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Engine runs at higher than normal temperature/overheats.
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POSSIBLE CAUSE
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• Improper coolant level
• Blown fuses
• Coolant leakage
• Excessive A/C system pressure
• A/C system operation is improper
• Improper water/anti‐freeze mixture
• Fans reverse rotation
• Poor radiator condition
• Thermostat malfunction
• Radiator hoses damage
• Improper or damaged radiator cap
• Cooling fan is inoperative.
• Coolant overflow system malfunction
• Improper tension of drive belt
• Drive belt damage
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Diagnostic procedure
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STEP |
INSPECTION |
RESULTS |
ACTION |
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1
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Inspect the following:
• Engine coolant level
• Coolant leakage
• Water and anti‐freeze mixture
• Radiator condition
• Collapsed or restricted radiator hoses
• Radiator pressure cap
• Overflow system
• Fan rotational direction
• Fuses
Are all items normal?
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Yes
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Go to the next step.
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No
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Service if necessary.
Repeat Step 1.
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2
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Connect the M-MDS to the DLC-2.
Retrieve any continuous memory, KOEO and KOER DTCs using M-MDS.
Are there any DTCs displayed?
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Yes
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DTC is displayed:
Go to the appropriate DTC inspection.
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No
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No DTC is displayed:
Go to the next step.
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3
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Start the engine and idle it.
Turn the A/C switch on.
Does the A/C compressor engage?
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Yes
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Go to Step 5.
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No
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Inspect for following and repair or replace if necessary:
• Refrigerant charging amount
• Open circuit in wiring harness between A/C relay and PCM terminal 1I*1, 1AN*2
• Seized A/C magnetic clutch
• A/C magnetic clutch malfunction
If all items are normal, go to the next step.
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4
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Connect the M-MDS to the DLC-2.
Access AC_REQ PID.
Start the engine and idle it.
Turn the A/C switch on.
Does AC_REQ PID read On?
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Yes
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Go to the next step.
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No
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Inspect the following:
• Refrigerant pressure switch operation
• The A/C switch is stuck open.
• Open or short circuit between refrigerant pressure switch and PCM terminal 1AU*1, 1AP*2
• Open circuit of blower motor fan switch and resistor (if blower motor does not operate)
• The evaporator temperature sensor and A/C amplifier
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5
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Inspect cooling fan control system operation.
Does the cooling fan control system function properly?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning part.
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6
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Is the drive belt normal?
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Yes
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Go to the next step.
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No
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Replace the drive belt.
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7
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Is there leakage around the heater unit in passenger compartment?
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Yes
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Inspect and service the heater for leakage.
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No
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Go to the next step.
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8
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Is there leakage at the coolant hoses and/or radiator?
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Yes
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Replace the malfunctioning part.
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No
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Go to the next step.
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9
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Cool down the engine.
Remove thermostat and inspect operation.
Is thermostat normal?
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Yes
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The ECT sensor and thermostat are normal.
Inspect engine block for leakage or blockage.
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No
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Access ECT PID.
Inspect for both ECT PID and temperature gauge readings.
• If temperature gauge on instrument cluster indicates normal range but ECT PID is not same as temperature gauge reading, inspect ECT sensor.
• If temperature gauge on instrument cluster indicates overheating but ECT PID is normal, inspect temperature gauge and heat gauge unit.
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10
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Verify test results.
• If normal, return to diagnostic index to service any additional symptoms.
• If malfunction remains, inspect related Service information perform repair or diagnosis.
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