Pinpoint Test J: Insufficient, Erratic Or No Heat

Climate Control System

Pinpoint Tests

Pinpoint Test J: 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 J: INSUFFICIENT, ERRATIC OR NO HEAT

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J1 CHECK FOR CORRECT ENGINE COOLANT LEVEL


- Ignition OFF.
- Check the engine coolant level when hot and when cold.
- Is the engine coolant at correct level (hot and cold) as indicated on the engine coolant recovery reservoir?

Yes
GO to J3.

No
GO to J2.

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J2 CHECK THE COOLANT SYSTEM INCLUDING THE RADIATOR CAP FOR LEAKS


- Pressure test the cooling system for leaks. Refer to Engine Cooling Testing and Inspection.
- Does the engine cooling system leak?

Yes
REPAIR the engine coolant leak. TEST the system for normal operation.

No
FILL and BLEED the cooling system. REFER to Engine Cooling Cooling System Draining, Filling and Bleeding. After filling and bleeding the cooling system, GO to J3.

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J3 CHECK FOR COOLANT FLOW TO THE HEATER CORE


- 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 J4.

No
REFER to Engine Cooling Description and Operation to check cooling system function.

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J4 CHECK FOR A PLUGGED OR RESTRICTED HEATER CORE


- 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 (6-17°C [10-30°F])?

Yes
Vehicles with manual climate control, GO to Pinpoint Test N Pinpoint Test N: Temperature Control Is Inoperative/Does Not Operate Correctly - Manual Climate Control. Vehicles with Electronic Automatic Temperature Control (EATC), GO to Pinpoint Test C. Pinpoint Test C: DTC B1249

No
CARRY OUT the Heater Core Component Test Climate Control System. REFER to Heater Core under Component Tests to determine whether a plugged or partial plugged condition exists.

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