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Shawn
Shawn, Auto Service Technician
Category: Ford
Satisfied Customers: 3756
Experience:  16 years experience Ford,Nissan and Honda dealership in all areas
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Ford: The heat control knob will not change the temp

Resolved Question:

Type your ford question here. The heat control knob will not change the temp. from cold to heat. Is there a fuse that controls this feature and if so which one?
Submitted: 3 years ago.
Category: Ford
Expert:  Shawn replied 3 years ago.
Hi JACUSTOMER-jw131c0m-.




Thank you for asking your question on JustAnswer. The most common cause of the problem you are having is most likely low coolant (see symptom chart below), if the coolant level is full and there are no leaks in the system, you may have a defective Temperature Blend Door Actuator (which is also very common on this vehicle), unfortunately there are no fuses to check or replace.

If you need I can also send you test procedures as well as replacement instructions, let me know.




  • Insufficient, Erratic, or No Heat
  • Low engine coolant level.
  • Engine overheating.
  • Plugged or partially plugged heater core.
  • Inoperative A/C electric blend door actuator.


Thank you again for trusting us with your problem. Please reply as soon as possible so that we can finish answering your question.
Shawn, Auto Service Technician
Category: Ford
Satisfied Customers: 3756
Experience: 16 years experience Ford,Nissan and Honda dealership in all areas
Shawn and 11 other Ford Specialists are ready to help you
Expert:  Shawn replied 3 years ago.
HiCustomer



Thank you for the ACCEPT!


The test procedures are below, if you additional help with this question, then please let me know, thanks again.

INSUFFICIENT, ERRATIC OR NO HEAT
CONDITIONSDETAILS/RESULTS/ACTIONS
B1 CHECK FOR PROPER ENGINE COOLANT LEVEL
graphicCheck the engine coolant level.

  • Is the engine coolant at the proper level in the coolant reservoir?
Yes GO to B2.
No GO to B3.
B2 CHECK FOR HOT WATER TO THE HEATER CONTROL VALVE INLET HOSE
WARNING: The heater core hoses will become too hot to handle and may cause serious burns if the system is working correctly.
Allow the engine to reach normal operating temperature.

On the 3.0L and 4.0L engines, feel the heater control valve inlet hose.
graphicOn the 2.5L engine, feel the heater control valve inlet hose.

  • Is the heater control valve inlet hose too hot to handle?
Yes GO to B4.
No REFER to Section 303-03.
B3 CHECK THE COOLANT SYSTEM INCLUDING THE RADIATOR CAP FOR LEAKS
graphicFill the coolant system to the specified "COLD FILL" level.
Pressure check the engine cooling system. Refer to Section 303-03.

  • Does the engine cooling system, including the radiator cap, hold pressure?
Yes GO to B4.
No Pressure test the heater core; REFER to the component test in this section.
B4 CHECK THE HEATER CORE INLET HOSE FOR HOT WATER
graphicFeel the heater core inlet hose.

  • Is the heater core inlet hose hot?
Yes GO to B5.
No GO to B6.
B5 CHECK THE HEATER CORE OUTLET HOSE FOR HOT WATER
graphicFeel the heater core outlet hose.

  • Is the heater core outlet hose warm or hot?
Yes GO to Pinpoint Test F.
No TEST the heater core for a plugged or partial-plugged condition; refer to the component test in this section.
B6 CHECK THE VACUUM SUPPLY TO THE HEATER CONTROL VALVE
Disconnect Heater Control Valve Vacuum Hose
graphicSelect any control function except "OFF" or "MAX A/C."
Check for the presence of vacuum at the heater control valve vacuum supply hose connector.

  • Is there vacuum present?
Yes REPLACE the heater water control valve (18495). TEST the system for normal operation.
No GO to B7.
B7 LEAK TEST THE VACUUM SUPPLY HOSE
Disconnect Function Selector Switch Vacuum Harness
graphicPlug the heater control valve hose at the heater control valve end.
graphicConnect a vacuum pump to the function selector switch vacuum harness connector and try to pull a vacuum.

  • Does the hose leak?
Yes INSPECT the in-line connector, and both engine-side and cabin-side hoses. REPLACE as necessary. TEST the system for normal operation.
No GO to B8.
B8 CHECK FOR A PLUGGED VACUUM SUPPLY HOSE
Remove the plug from the heater control valve end of the hose.
graphicConnect a vacuum pump to the function selector switch vacuum harness connector and try to pull a vacuum. If the pump can pull and hold a vacuum, the hose is plugged. If the pump pulls a vacuum that slowly decays, the hose is restricted.

  • Is the hose plugged or restricted?
Yes REPLACE the vacuum hose. TEST the system for normal operation.
No GO to Pinpoint Test E




 

PINPOINT TEST E: NO OPERATION IN ALL TEMPERATURE SETTINGS
CONDITIONSDETAILS/RESULTS/ACTIONS
E1 CHECK THE TEMPERATURE CONTROL
Start the engine and run at idle. Allow the engine to reach normal operating temperature.
graphicPlace the function selector switch in the FLOOR position.
graphicAdjust the temperature control to full warm position, and physically feel the discharge air temperature at the heater outlet floor duct.
graphicRotate the temperature control to full cool position, and physically feel the discharge air temperature at the heater outlet floor duct.

  • Does the discharge air temperature vary?
Yes The temperature blend door is functioning properly. RETURN to the symptom chart.
No GO to E2.
E2 CHECK FUSE 10 (7.5A)
Disconnect Fuse Junction Panel Fuse 10 (7.5A)
graphicTest Fuse Junction Panel Fuse 10 (7.5A)

  • Is Fuse 10 (7.5A) OK?
Yes GO to E7.
No GO to E3.
E3 CHECK CIRCUIT 1003 (GY/Y) FOR A SHORT TO GROUND
Disconnect Function Selector Switch C234
graphicMeasure the resistance between the function selector switch connector Pin C234-4, Circuit 1003 (GY/Y), and ground.

  • Is the resistance greater than 10,000 ohms?
Yes GO to E4.
No GO to E6.
E4 CHECK CIRCUIT 348 (P) FOR A SHORT TO GROUND
Disconnect PCM C111
graphicMeasure the resistance between the function selector switch connector Pin C234-3, Circuit 348 (P) and ground.

  • Is the resistance greater than 10,000 ohms?
Yes GO to E5.
No REPAIR Circuit 348 (P) for a short to ground. TEST the system for normal operation.
E5 CHECK FOR A SHORTED FUNCTION SELECTOR SWITCH
Connect Function Selector Switch C234
graphicNOTE: Make sure Fuse 10 (7.5A) is still removed.
    Measure the resistance between the powertrain control module connector Pin C111-41, Circuit 348 (P) and ground.
Turn the function selector switch to each of the following positions and note the resistance reading.
  • MAX A/C
  • PNL/FLR
  • DEF
  • A/C
  • FLR/DEF

  • Are any of the resistance readings 10,000 ohms or less?

Yes REPLACE the function selector switch. TEST the system for normal operation.
No REPLACE Fuse 10 (7.5A). TEST the system for normal operation. If Fuse 10 (7.5A) opens again, REPLACE the powertrain control module.

TEST the system for normal operation.

E6 CHECK THE BLEND DOOR ACTUATOR
Disconnect Blend Door Actuator C240
graphicMeasure the resistance between the function selector switch connector Pin C234-4, Circuit 1003 (GY/Y) and ground.

  • Is the resistance reading 10,000 ohms or less?
Yes REPAIR Circuit 1003 (GY/Y) for a short to ground. TEST the system for normal operation.
No REPLACE the A/C electronic door actuator motor; TEST the system for normal operation.
E7 CHECK THE SUPPLY TO THE BLEND DOOR ACTUATOR
Disconnect Blend Door Actuator C240
graphicMeasure the voltage at the blend door actuator connector Pin C240-7, Circuit 1003 (GY/Y).

  • Is the voltage greater than 9 volts?
Yes GO to E8.
No REPAIR Circuit 1003 (GY/Y) for an open. TEST the system for normal operation.
E8 CHECK THE GROUND TO THE BLEND DOOR ACTUATOR
graphicMeasure the resistance between the blend door actuator connector Pin C240-8, Circuit 57 (BK) and ground.

  • Is the resistance reading less than 10,000 ohms?
Yes GO to E9.
No REPAIR Circuit 57 (BK) for an open. TEST the system for normal operation.
E9 CHECK THE TEMPERATURE BLEND CONTROL LOW SIDE OPERATION
graphicMeasure the resistance between the blend door actuator connector Pins C240-6, Circuit 359 (GY/R) and C240-3, Circuit 773 (DG/O) while rotating the temperature blend control from full warm to full cool.

  • Does the resistance vary from 150 ohms to 4700 ohms?
Yes GO to E12.
No GO to E10.
E10 CHECK CIRCUIT 359 (GY/R) FOR AN OPEN
graphicMeasure the resistance between the temperature blend control connector Pin C231-3, Circuit 359 (GY/R), and the blend door actuator connector Pin C240-6.

  • Is the resistance less than 5 ohms?
Yes GO to E11.
No REPAIR Circuit 359 (GY/R). TEST the system for normal operation.
E11 CHECK CIRCUIT 773 (DG/O) FOR AN OPEN
graphicMeasure the resistance between the temperature blend control connector Pin C231-2, Circuit 773 (DG/O), and the blend door actuator connector Pin C240-3.

  • Is the resistance less than 5 ohms?
Yes REPLACE the temperature blend control; TEST the system for normal operation.
No REPAIR Circuit 773 (DG/O). TEST the system for normal operation.
E12 CHECK THE TEMPERATURE BLEND CONTROL HIGH SIDE OPERATION
graphicMeasure the resistance between the blend door actuator connector Pins C240-4, Circuit 660 (Y/LG) and C240-3, Circuit 773 (DG/O) while rotating the temperature blend control from full warm to full cool.

  • Does the resistance vary from 150 ohms to 4700 ohms?
Yes GO to E14.
No GO to E13.
E13 CHECK CIRCUIT 660 (Y/LG) FOR AN OPEN
graphicMeasure the resistance between the temperature blend control connector Pin C231-1, Circuit 660 (Y/LG), and the blend door actuator connector Pin C240-4.

  • Is the resistance less than 5 ohms?
Yes REPLACE the temperature blend control; TEST the system for normal operation.
No REPAIR Circuit 660 (Y/LG). TEST the system for normal operation.
E14 CHECK CIRCUIT 359 (GY/R) FOR A SHORT TO GROUND
graphicMeasure the resistance between the temperature blend control connector Pin C231-3, Circuit 359 (GY/R), and ground.

  • Is the resistance greater than 10,000 ohms?
Yes GO to E15.
No REPAIR Circuit 359 (GY/R). TEST the system for normal operation.
E15 CHECK CIRCUIT 773 (DG/O) FOR A SHORT TO GROUND
graphicMeasure the resistance between temperature blend control connector Pin C231-2, Circuit 773 (DG/O), and ground.

  • Is the resistance greater than 10,000 ohms?
Yes GO to E16.
No REPAIR Circuit 773 (DG/O). TEST the system for normal operation.
E16 CHECK CIRCUIT 660 (Y/LG) FOR A SHORT TO GROUND
graphicMeasure the resistance between the temperature blend control connector Pin C231-1, Circuit 660 (Y/LG), and ground.

  • Is the resistance greater than 10,000 ohms?
Yes REPLACE the A/C electronic door actuator motor motor; TEST the system for normal operation.
No REPAIR Circuit 660 (Y/LG). TEST the system for normal operation.



Thank you again for trusting us with your problem. Please reply as soon as possible so that we can finish answering your question.

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