Pinpoint Test J: Insufficient, Erratic Or No Heat

WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

J1 CHECK FOR PROPER ENGINE COOLANT LEVEL
- Key in OFF position.
- 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 J3.

No

GO to J2.
J2 CHECK THE ENGINE COOLING SYSTEM FOR LEAKS
- Pressure test the cooling system for leaks. refer to ENGINE COOLING .
- Does the engine cooling system leak?
Yes

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

No

GO to J3.
J3 CHECK FOR COOLANT FLOW TO THE HEATER CORE
WARNING: The heater core inlet hose will become too hot to handle and may cause serious burns if the system is working correctly.
- Run the engine until it reaches normal operation temperature. Select the FLOOR position on the control assembly. Set the temperature control to full WARM.
- Feel the heater core inlet hose to see if it is hot.
  
  Fig 1: Checking Heater Core Inlet Hose For Heat
  Courtesy of FORD MOTOR CO.
- Is the heater core inlet hose hot?
Yes

GO to J9.

No

GO to J4.
J4 CHECK FOR COOLANT FLOW TO THE HEATER CONTROL VALVE
WARNING: The heater control valve inlet hose will become too hot to handle and may cause serious burns if the system is working correctly.
- Feel the heater control valve inlet hose to see if it is hot.
  
  Fig 2: Checking Coolant Flow To Heater Control Valve
  Courtesy of FORD MOTOR CO.
- Is the heater control valve inlet hose hot?
Yes

GO to J5.

No

refer to ENGINE COOLING .
J5 CHECK FOR VACUUM AT THE HEATER CONTROL VALVE
- Disconnect the heater control valve vacuum connector and check for vacuum.
  
  Fig 3: Checking Vacuum At Heater Control Valve
  Courtesy of FORD MOTOR CO.
- Is vacuum present at the heater control valve?
Yes

GO to J6.

No

INSTALL a new heater control valve. REFER to HEATER CONTROL VALVE AND HEATER HOSES - 4.0L SOHC or HEATER CONTROL VALVE AND HEATER HOSES - 4.6L (2V) . TEST the system for normal operation.
J6 CHECK FOR INCORRECT VACUUM LINE PLACEMENT
- Key in OFF position.
- 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 J7.

No

CORRECT the vacuum line placement. TEST the system for normal operation.
J7 CHECK THE CIRCUIT FOR VOLTAGE
- Key in OFF position.
- Disconnect: ATC Solenoid and Manifold C2093.
- Key in ON position.
- Measure the voltage between the ATC solenoid and manifold C2093-6, circuit 1069 (OG/LB) and ground.
  
  Fig 4: Checking Circuit Voltage
  Courtesy of FORD MOTOR CO.
- Is voltage present?
Yes

GO to J8

No

INSTALL a new ATC solenoid and manifold. TEST the system for normal operation.
J8 CHECK THE CIRCUIT FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Disconnect: DATC Module C228a.
- Key in ON position.
- Measure the voltage between the ATC solenoid and manifold C2093-6, circuit 1069 (OG/LB) and ground.
  
  Fig 5: Checking Circuit For Short To Voltage
  Courtesy of FORD MOTOR CO.
- Is voltage present?
Yes

REPAIR circuit 1069 (OG/LB) for a short to voltage. TEST the system for normal operation.

No

INSTALL a new DATC module. TEST the system for normal operation.
J9 CHECK FOR A PLUGGED OR RESTRICTED HEATER CORE
WARNING: The heater core outlet hose will become too hot to handle and may cause serious burns if the system is operating correctly.
- Feel the heater core outlet hose to see if it is hot.
  
  Fig 6: Checking Heater Core Inlet Hose For Heat
  Courtesy of FORD MOTOR CO.
- Is the heater core outlet hose hot?
Yes

For manual climate control systems, GO to PINPOINT TEST M .

For DATC systems, GO to PINPOINT TEST A .

No

INSTALL a new heater core. REFER to HEATER CORE - FRONT . TEST the system for normal operation.