Pinpoint Test I: Insufficient, Erratic Or No Heat

WARNING: This page is about a different car, the 2006 Ford Pickup, 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

I1 CHECK FOR CORRECT 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 I3.

No : GO to I2.
I2 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 I3.
I3 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.
- Key in ON position.
- 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: Identifying Heater Core Inlet Hose
  Courtesy of FORD MOTOR CO.
- Is the heater core inlet hose hot?
Yes : GO to I7.

No : GO to I4.
I4 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 For Coolant Flow To Heater Control Valve
  Courtesy of FORD MOTOR CO.
- Is the heater control valve inlet hose hot?
Yes : GO to I5.

No : REFER to ENGINE COOLING .
I5 CHECK FOR VACUUM AT THE HEATER CONTROL VALVE
NOTE: Vacuum should not be present in FLOOR and full WARM. Vacuum should only be present in MAX A/C.
- Disconnect the heater control valve vacuum connector and check for vacuum.
  
  Fig 3: Checking For Vacuum Heater Control Valve
  Courtesy of FORD MOTOR CO.
- Is vacuum present at the heater control valve?
Yes : GO to I6.

No : INSTALL a new heater control valve. TEST the system for normal operation.
I6 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 : Vehicles with manual climate control, INSTALL a new climate control assembly. TEST the system for normal operation.

Vehicles with EATC, GO to I8.

No : CORRECT the vacuum line placement. TEST the system for normal operation.
I7 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 4: Locating Heater Core Outlet Hose
  Courtesy of FORD MOTOR CO.
- Is the heater core outlet hose hot?
Yes : Vehicles with manual climate control, GO to PINPOINT TEST L .

Vehicles with EATC, GO to PINPOINT TEST A .

No : INSTALL a new heater core. REFER to CLIMATE CONTROL . TEST the system for normal operation.
I8 CHECK THE CIRCUIT FOR AN OPEN
- Key in OFF position.
- Disconnect: EATC Module C228a.
- Disconnect: RSA Module C2093.
- Measure the resistance between the EATC module C228a-11, circuit 1111 (VT) and the RSA module C2093-6, circuit 1111 (VT).
  
  Fig 5: Checking Circuit For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : INSTALL a new RSA module. REFER to CLIMATE CONTROL . TEST the system for normal operation.

No : REPAIR circuit 1111 (VT) for an open. TEST the system for normal operation.