Pinpoint Test N: Insufficient, Erratic or No Heat
Climate Control System
Pinpoint Tests
Pinpoint Test N: Insufficient, Erratic or No Heat
Normal Operation
Under normal operation, warm coolant flows from the engine through the heater core and back to the engine.
This pinpoint test is intended to diagnose the following:
- Plugged heater core
- Coolant level
- Temperature blend door
PINPOINT TEST N: INSUFFICIENT, ERRATIC OR NO HEAT
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N1 CHECK FOR CORRECT ENGINE COOLANT LEVEL
- Ignition OFF.
- Check the engine coolant level when hot and cold.
- Is the engine coolant at the correct level (hot and cold)?
Yes
GO to N3.
No
GO to N2.
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N2 CHECK THE COOLANT SYSTEM INCLUDING THE RADIATOR CAP FOR LEAKS
- Fill the engine cooling system to the specified level.
- Pressure check the engine cooling system, including the radiator cap. Refer to Cooling System. It is not necessary to check the components separately at this time.
- Does the engine cooling system, including the radiator cap, hold pressure?
Yes
GO to N3.
No
REPAIR the cooling system leak. TEST the system for normal operation.
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N3 CHECK FOR HOT WATER TO THE HEATER CORE INLET HOSE
- Run the engine until it reaches normal operation temperature. Select the FLOOR position on the control assembly. Set the temperature control to full warm and the blower to the lowest setting.
- Using a suitable temperature measuring device, check the heater core inlet hose to see if it is hot.
- Is the heater core inlet hose hot?
Yes
GO to N4.
No
GO to Cooling System to check the cooling system function.
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N4 CHECK THE HEATER CORE OUTLET HOSE FOR HOT WATER
- Using a suitable temperature measuring device, measure the heater core outlet hose temperature.
- Is the heater core outlet hose temperature similar to the inlet hose temperature (within approximately 6-17°C [10-30°F])?
Yes
Go To Pinpoint Test A. Pinpoint Test A: DTC P0532 or P0533
No
CARRY OUT the Heater Core Component Test. REFER to Heater Core under Component Tests to determine whether a plugged or partial-plugged condition exists. Heater Core
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