Pinpoint Test K: Insufficient, Erratic Or No Heat

Climate Control System

Pinpoint Tests

Pinpoint Test K: Insufficient, Erratic or No Heat

Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number

Normal Operation

Under normal operation, for Dual Automatic Temperature Control (DATC) systems, the solenoid and manifold assembly receives a ground from the HVAC module - DATC. When the heater control valve vacuum solenoid is to be energized, the solenoid and manifold assembly receives voltage from the HVAC module - DATC.

Under normal operation, for manual climate control systems, the function selector switch receives engine vacuum. When OFF or MAX A/C is selected, vacuum is applied to the recirculation vacuum control motor. When the temperature is in the full COOL position, the heater control valve vacuum switch applies vacuum to the heater control valve.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Solenoid and manifold assembly (DATC systems only)
- HVAC module - DATC
- Function selector switch (manual climate control systems only)
- Heater control valve
- Heater control valve vacuum switch (if equipped)
- Stuck or bound linkage or door
- Leaking or plugged vacuum hose
- Temperature blend door actuator



PINPOINT TEST K: INSUFFICIENT, ERRATIC OR NO HEAT

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K1 CHECK FOR PROPER ENGINE COOLANT LEVEL


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

Yes
GO to K3.

No
GO to K2.

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K2 CHECK THE ENGINE COOLING SYSTEM FOR LEAKS


- Pressure test the cooling system for leaks. Refer to Cooling System &/or Engine Block Heater.
- 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 Cooling System &/or Engine Block Heater. After filling and bleeding the cooling system, GO to K3.

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K3 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 K9.

No
GO to K4.

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K4 CHECK FOR COOLANT FLOW TO THE HEATER CONTROL VALVE


- Using a suitable temperature measuring device, measure the heater control valve inlet hose to see if it is hot.




- Is the heater control valve inlet hose hot?

Yes
GO to K5.

No
REFER to Cooling System &/or Engine Block Heater.

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K5 CHECK FOR VACUUM AT THE HEATER CONTROL VALVE


- Disconnect the heater control valve vacuum connector and check for vacuum.




- Is vacuum present at the heater control valve?

Yes
GO to K6.

No
INSTALL a new heater control valve. TEST the system for normal operation.

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K6 CHECK FOR INCORRECT VACUUM LINE PLACEMENT


- Ignition OFF.
- Inspect the heater control valve and A/C vacuum lines for correct placement.
- Is the vacuum line placement correct?

Yes
For manual climate control systems, INSTALL a new heater control valve vacuum switch.
For DATC systems, GO to K7 .

No
CORRECT the vacuum line placement. TEST the system for normal operation.

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K7 CHECK THE CIRCUIT FOR VOLTAGE


- Ignition OFF.
- Disconnect: Solenoid and Manifold Assembly C2093.
- Ignition ON.
- Measure the voltage between ground and solenoid and manifold assembly C2093-6, circuit CH224 (BU/OG), harness side.




- Is any voltage present?

Yes
GO to K8.

No
INSTALL a new solenoid and manifold assembly. TEST the system for normal operation.

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K8 CHECK THE CIRCUIT FOR A SHORT TO VOLTAGE


- Ignition OFF.
- Disconnect: HVAC Module - DATC C228A.
- Ignition ON.
- Measure the voltage between ground and solenoid and manifold assembly C2093-6, circuit CH224 (BU/OG), harness side.




- Is any voltage present?

Yes
REPAIR circuit CH224 (BU/OG) for a short to voltage. TEST the system for normal operation.

No
INSTALL a new HVAC module - DATC. TEST the system for normal operation.

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K9 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 (within approximately 6-17°C [10-30°F])?

Yes
For manual climate control systems, GO to Pinpoint Test O. Pinpoint Test O: The Temperature Control Is Inoperative/Does Not Operate Correctly - Manual Climate Control

For DATC systems, GO to Pinpoint Test C. Pinpoint Test C: DTC B2266 Or B2267

No
INSTALL a new heater core. TEST the system for normal operation.

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