NO.19 COOLING SYSTEM CONCERNS-OVERHEATING [MZR-CD (RF Turbo)]

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19

COOLING SYSTEM CONCERNS-OVERHEATING

DESCRIPTION

•  Engine runs at higher than normal temperature/overheats.

POSSIBLE CAUSE

•  Cooling fan malfunction

•  Low drive belt tension

•  Drive belt damage

•  Improper coolant level

•  Thermostat malfunction

•  Radiator clogging

•  Improper water/anti-freeze mixture

•  Improper or damaged radiator cap

•  Radiator hose damage

•  Coolant leakage (engine internal, turbocharger, external)

•  A/C system malfunction

•  EGR system malfunction

•  Coolant heater system malfunction

19	COOLING SYSTEM CONCERNS-OVERHEATING
DESCRIPTION	• Engine runs at higher than normal temperature/overheats.
POSSIBLE CAUSE	• Cooling fan malfunction • Low drive belt tension • Drive belt damage • Improper coolant level • Thermostat malfunction • Radiator clogging • Improper water/anti-freeze mixture • Improper or damaged radiator cap • Radiator hose damage • Coolant leakage (engine internal, turbocharger, external) • A/C system malfunction • EGR system malfunction • Coolant heater system malfunction

Diagnostic Procedure

STEP	INSPECTION	RESULTS	ACTION
1	Inspect the following: • Engine coolant level • Coolant leakage (around heater unit in passenger compartment, coolant hoses and/or radiator, and around coolant heater unit.) • Water and anti-freeze mixture • Radiator condition • Collapsed or restricted radiator hoses • Radiator pressure cap • Drive belt tension • Drive belt • Fan rotational direction Are all items normal?	Yes	Go to the next step.
1		No	Service if necessary. Repeat Step 1.
2	Perform the self-test function using the M-MDS. Turn the engine switch to the ON position. Retrieve any DTCs. Are any DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC test. (See DTC TABLE [MZR-CD (RF Turbo)].) Communication error message is displayed: Inspect the following: • Open circuit between PCM control relay and PCM terminal 119 or 120 • Open circuit PCM control relay and PCM terminal 105 • PCM control relay stuck open • Open or poor ground circuit (PCM terminal 1, 2, 3, 114 or 117) • Poor connection to vehicle body ground
2		No	No DTC is displayed: Go to the next step.
3	Note • The following test should be performed on the vehicles with an A/C system. Go to the next step for vehicles without an A/C system Start the engine and run it at idle speed. Turn the A/C switch off. Does the A/C compressor disengage?	Yes	Go to the next step.
3		No	Go to the symptom troubleshooting “NO.26 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR-CD (RF-Turbo)]”. (See NO.26 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR-CD (RF Turbo)].)
4	Perform the Cooling Fan Control System Operation Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR-CD (RF Turbo)].) Does the cooling fan system work properly.	Yes	Go to the next step.
4		No	Repair or replace the malfunctioning part according to inspection result.
5	Is the drive belt normal?	Yes	Go to the next step.
5	Is the drive belt normal?	No	Replace the drive belt.
6	Perform the EGR system inspection. Is the EGR system normal?	Yes	Go to the next step.
6		No	Repair or replace the malfunctioning part according to the EGR system operation results.
7	Perform the coolant heater system inspection. (See THERMOSTAT INSPECTION [MZR-CD (RF Turbo)].) Is the coolant heater system normal?	Yes	Go to the next step.
7		No	Repair or replace the malfunctioning part according to the coolant heater system operation results.
8	Cool down engine. Remove the thermostat and inspect the operation. Is the thermostat normal?	Yes	Thermostat is normal. Inspect the cylinder block for leakage or blockage.
8		No	Replace thermostat.
9	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR-CD (RF Turbo)].) • If the malfunction remains, inspect the related Service Information and perform repair or diagnosis. ― If the vehicle is repaired, troubleshooting completed. ― If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if later calibration is available. Retest.