AutoZone 1966 Nissan/Datsun Truck 520 1.3L 2BL OHV 4cyl | Repair Guides | Engine Cooling | Engine Fan | Electric Engine Fan | AutoZone.com

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    Volkswagen Cars 2000-05

    Electric Engine Fan

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    Electric Fan Switch



    The electric fan switch, mounted in the radiator, supplies power to the fan (via relay) when the coolant reaches a certain temperature.

    The engine's electric fan switch is mounted into the cooling passage of the radiator or into one of the lower coolant pipes coming from the bottom of the radiator. The fan switch is a temperature sensitive two stage thermal switch that remains open (OFF) until the coolant reaches a certain temperature.

    The 2-stage thermal switch essentially is 2 thermal switches that have been combined into one thermal switch. The stage 1 or low speed circuit is closed (ON) when the coolant temperature reaches approximately 203°F (95°C). The stage 2 or high speed circuit is closed (ON) when the coolant temperature reaches approximately 221°F (105°C).

    The thermal switch has three terminals and is used to complete a series circuit. On 1990-93 Passat models, the thermal is fed positive battery current and the switch, when closed (ON), completes the circuit for the positive battery voltage for the cooling fan(s).

    The thermal switch used on A4 and 1994 and later Passat models is used to complete a series circuit that supplies ground to trigger a relay, which is used to complete the positive battery voltage for the cooling fan(s).



    Click image to see an enlarged view

    Fig. The cooling fan thermal switch is located on the bottom corner of the radiator on 1.8L Passat models

    Operation

    Operation of the cooling fan is dependent on several factors, which include proper thermostat operation, A/C operation, and other switches, including the after-run thermoswitch. Before testing the thermal electric fan switch, quickly verify the operation of the electric cooling fan(s). Make sure that the cooling system is functioning properly, as problems such as a restricted radiator will cause overheating problems and may exhibit the same symptoms as a cooling fan malfunction. Make sure all the fuses, electrical connections, and wires are intact.


    CAUTION
    Keep clear of the radiator fan blades. The fan can operate at any time.

    1. Unplug the electrical harness connector from the thermal fan switch.
    2.  
    3. Check for ground at terminal 3 (brown wire). If ground is not present, check the wiring and repair as necessary. The cooling fan operation can still be verified if a suitable jumper wire is used to supply ground. If doing so, connect the jumper wire used for probing the electrical connector to the alternate source of ground and substitute the alternate ground instead of terminal 3 (brown wire) and proceed with testing.
    4.  
    5. Turn the ignition switch to the ON position, but Do NOT start the engine.
    6.  
    7. Using a suitable jumper wire, carefully connect the jumper between terminals 2 (green wire with black tracer) and 3 (brown wire). The radiator cooling fan should operate at low speed.
    8.  
    9. Using a suitable jumper wire, connect the jumper between terminals 1 (red wire with green tracer) and 3 (brown wire). The radiator fan should operate at high speed.
    10.  
    11. If the radiator fan operates properly at both speeds, and ground is available at terminal 3 (brown wire), the radiator fan switch is faulty and should be replaced.
    12.  
    13. If the radiator fan does not operate, check the relays, radiator fan or the wiring circuit for broken terminals, blown fuses, cut wires, etc. For additional information, please refer to the following topic(s): Chassis Electrical, Wiring Diagrams.
    14.  

    Removal & Installation
    1. Raise and safely support the front of the vehicle on jackstands.
    2.  
    3. If applicable, remove the lower splash shield to access the switch.
    4.  
    5. Remove the coolant reservoir cap to ensure there is no pressure in the cooling system.
    6.  
    7. Disconnect the harness connector from the sensor.
    8.  


    NOTE
    If the switch is being replaced, draining of the cooling system can be eliminated by having a new switch ready at the time of removal. A small amount of coolant will be lost, but refilling the system will not be necessary. Alternately, complete draining of the cooling system will be necessary for replacement of the fan switch.

    1. Place a drain receptacle underneath the switch.
    2.  
    3. Loosen the switch with a wrench until it can be turned by hand.
    4.  
    5. While pushing inward, unscrew the switch until the threads are free. Make sure to push inward on the switch with force; the pressure of the coolant will push outward. Keep a firm grip on the switch.
    6.  
    7. With the new switch (and new gasket placed on the switch) in your opposite hand, pull the old switch away from the radiator as quickly as possible while positioning the new switch in its place. Do this as fast as possible to prevent coolant from escaping from the radiator. Once positioned, screw the new switch into the radiator quickly to prevent coolant loss.
    8.  
    9. Tighten the switch to 18-26 ft. lbs. (25-35 Nm).
    10.  
    11. Plug the harness connector into the switch.
    12.  
    13. As applicable, install the lower splash shield.
    14.  
    15. Lower the vehicle from the jackstands.
    16.  
    17. Adjust the level of the cooling system as necessary.
    18.  



    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.


    CAUTION
    Engine coolant can spray out causing severe burns if the Engine Coolant Temperature (ECT) gauge sending unit is removed from a hot engine without allowing the engine to cool below 100°F (37°C) and draining the engine coolant into a sealable container first.

    1. Allow the engine to cool below 100°F (37°C) before working on the cooling system.
    2.  
    3. Note the anti-theft code and radio presets for the radio.
    4.  
    5. Disconnect the negative battery cable.
    6.  
    7. Raise and safely support the front of the vehicle on jackstands.
    8.  
    9. If necessary, remove the lower engine shield.
    10.  
    11. Locate the cooling fan thermal switch.
    12.  
    13. Drain the engine coolant into a sealable container.
    14.  
    15. Detach the electrical connector.
    16.  
    17. If the thermal switch is held into the coolant passage with a retaining clip:
    18.  
      1. Remove the thermal switch retaining clip, and pull the thermal switch straight out of the housing.
      2.  

    19. If the thermal switch is threaded into the coolant passage:
    20.  
      1. Loosen the thermal switch using a crowfoot wrench, a suitable boxed end wrench or a thin-walled 3 / 8 inch drive 12-point, deep-well socket and breaker bar.
      2.  


    To install:

    1. If the thermal switch is held into the coolant passage with a retaining clip:
    2.  
      1. Install a new O-ring on the sensor.
      2.  
      3. Using a small amount of fresh coolant or an anti-seizing compound, lightly lubricate the O-ring, and push the thermal switch in the housing.
      4.  
      5. While pushing inward on the thermal switch, install the retaining clip.
      6.  

    3. If the thermal switch threaded into the coolant passage:
    4.  
      1. Install the sensor with a new crush washer and tighten to 26 ft. lbs. (35 Nm).
      2.  

    5. Plug in the harness connector to the thermal switch.
    6.  
    7. As applicable, install the lower splash shield.
    8.  
    9. Lower the vehicle from the jackstands.
    10.  
    11. Refill the cooling system with the proper type and mixture of coolant and bleed as necessary. For additional information, please refer to the following topic(s): General Information and Maintenance, Fluids and Lubricants.
    12.  
    13. Reconnect the negative battery cable and re-code the radio as necessary.
    14.  
    15. Start the engine, check for normal operation and fluid leaks.
    16.  



    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.

    Testing

    Operation of the cooling fan is dependent on several factors, which include proper thermostat operation, A/C operation, and other switches, including the after-run thermoswitch. Before testing the radiator-mounted electric fan switch, verify that the cooling system is functioning properly, and that all electrical connections and wires are intact.


    CAUTION
    Keep clear of the radiator fan blades. The fan can operate at any time.

    1. Unplug the electrical harness connector from the radiator fan switch.
    2.  
    3. Using a suitable jumper wire, connect the red terminal on the harness connector to the red/white wire. The radiator fan should operate at low speed.
    4.  
    5. Using a suitable jumper wire, connect the red terminal on the harness connector to the red/black wire. The radiator fan should operate at high speed.
    6.  
    7. If the radiator fan operates properly at both speeds, the radiator fan switch is faulty and should be replaced.
    8.  
    9. If the radiator fan does not operate, check the radiator fan wiring circuit for broken terminals, blown fuses, cut wires, etc. Refer to Section 6 for more information.
    10.  

    The electric cooling fan switch is installed into a coolant passage and operates the radiator auxiliary electric cooling fan when the coolant temperature reaches a specified temperature or when the air conditioner is activated. The fan has operates in two stages depending on the engine coolant temperature.


    NOTE
    In normal conditions, if the air conditioner is in proper working order, the engine cooling fans will operate when the air conditioner is turned on, because the A/C operation overrides the thermal switch, regardless of the coolant temperature. When testing the electric cooling fan circuit, make sure the air conditioner is OFF.

    Switch Installed

    CAUTION
    Do NOT allow the engine to operate continuously without the aid of the auxiliary cooling fan otherwise severe engine damage will occur.

    1. Locate the cooling fan switch mounted on the radiator.
    2.  
    3. Detach the wire connector from the fan switch.
    4.  
    5. To test stage 1 of the fan switch, using a suitable ohmmeter or continuity tester check for continuity between the fan switch terminals 2 and 3 .
    6.  
    7. Allow the engine to reach a coolant temperature as follows. The fan switch should have continuity (switch closed) at this temperature:
    8.  

    1990-93 Passat models:



    Stage 1: 203°F (95°C)
     

    A4 and 1994-00 Passat models:



    Stage 1: 198-207°F (92-97°C)
     

    1. To test stage 2 of the fan switch, using a suitable ohmmeter or continuity tester check for continuity between the fan switch terminals 1 and 3 .
    2.  
    3. Allow the engine to reach a coolant temperature as follows. The fan switch should have continuity (switch closed) at this temperature:
    4.  

    1990-93 Passat models:



    Stage 2: 221°F (105°C)
     

    A4 and 1994-00 Passat models:



    Stage 2 : 210-221°F (99-105°C)
     

    1. The thermal switch should be open (off) as follows:
    2.  


      Stage 1: 183-196°F (84-91°C)
       
      Stage 2 : 196-208°F (91-98°C)
       

    3. If the switch does not operate within the range of the supplied information, replace the switch.
    4.  

    Switch Removed

    WARNING
    Submerging the electric cooling fan switch below the threads could damage the component. Perform this procedure in a safe and well-ventilated area. Wear eye protection and use care to not come in contact with any of the heated components. Do NOT use a heating device that produces an open flame.

    Testing a radiator fan switch is not difficult, however to do so requires some basic equipment. To properly test the fan switch, the switch's probe must be submersed in heated coolant, only as far as the component's threads. The coolant must be heated while the temperature is monitored. When the coolant reaches the specified temperature, the fan switch should be closed. Use suitable fitting electrical jumper leads to avoid contact with the heated coolant during testing. Testing the switch requires the following equipment:



    A safe source of heat, such as a portable electric hot plate
     
    A container capable of being safely heated by a hot plate and handling heated coolant
     
    A thermometer safely capable of reading 221°F (105°C)
     
    A device to safely hold the switch such that only the coolant probe is submerged into the coolant
     
    An ohmmeter or continuity tester
     

    1. Refer to the cooling fan switch removal and installation warning and procedures and remove the switch.
    2.  
    3. Attach a 12 inch wiring sub-harness to the cooling fan switch to avoid having to probe the switch while in the heated coolant. Place the switch into a suitable holding device such that the temperature probe of the switch is submersed in a container of heated coolant. Make sure the container can be safely heated using a suitable source of heat such as a portable electric hot plate.
    4.  
    5. Using a suitable thermometer to measure the coolant temperature, heat the coolant until the specified temperature is attained.
    6.  
    7. To test stage 1 of the fan switch, using a suitable ohmmeter or continuity tester check for continuity between the fan switch terminals 2 and 3 . The cooling fan switch should have continuity (closed) between the electrical terminals 2 and 3 at the following temperatures:
    8.  

    1990-93 Passat models:



    Stage 1: 203°F (95°C)
     

    A4 and 1994-00 Passat models:



    Stage 1: 198-207°F (92-97°C)
     

    1. To test stage 2 of the fan switch, using a suitable ohmmeter or continuity tester check for continuity between the fan switch terminals 1 and 3 . The cooling fan switch should have continuity (closed) between the electrical terminals 1 and 3 at the following temperatures:
    2.  

    1990-93 Passat models:



    Stage 2: 221°F (105°C)
     

    A4 and 1994-00 Passat models:



    Stage2 : 210-221°F (99-105°C)
     

    1. The thermal switch should be open (off) as follows:
    2.  


      Stage 1: 183-196°F (84-91°C)
       
      Stage 2 : 196-208°F (91-98°C)
       

    3. If the switch does not operate within the range of the supplied information, replace the switch.
    4.  

    Removal & Installation



    1. Disconnect the negative battery cable.
    2.  
    3. Remove the radiator assembly.
    4.  
    5. Remove the cooling fan shroud from the radiator assembly.
    6.  
    7. Remove the fan from the motor.
    8.  
    9. If necessary, remove the motor assembly.
    10.  
    11. Installation is in reverse order of removal.
    12.  



    Click image to see an enlarged view

    Fig. Exploded view of the typical radiator and fan assembly found on 1990-97 Passat models



    Click image to see an enlarged view

    Fig. Detach all wiring harnesses necessary for radiator removal



    Click image to see an enlarged view

    Fig. Use caution not to snap off any plastic wiring clips



    Click image to see an enlarged view

    Fig. The radiator fan assembly



    Click image to see an enlarged view

    Fig. Remove the fasteners and then the fan assembly from the radiator



    Click image to see an enlarged view

    Fig. The secondary fan is driven by a belt via the primary motor



    Click image to see an enlarged view

    Fig. Remove the secondary fan rubber drive belt



    Click image to see an enlarged view

    Fig. Detach the plastic retaining ring



    Click image to see an enlarged view

    Fig. To remove the fan blades, detach the locking ring tab and then the center nut



    Click image to see an enlarged view

    Fig. View of fan blade nut and locking tab



    Click image to see an enlarged view

    Fig. Note the position of the fan motor wiring connectors location to the steel housing. The motor can be put in upside down



    Click image to see an enlarged view

    Fig. Remove the electric fan motor mounting bolts



    Click image to see an enlarged view

    Fig. Remove the radiator fan motor

    Testing



    The electric cooling fan operation is controlled by the engine cooling fan thermal switch and, if equipped, by the air conditioner. When the air conditioner is operating properly the electric cooling fans should be activated.

    On some models, the cooling fans will operate for a short period of time when the engine is shut off if the coolant is above a given temperature. This prevents over heating, helps with hot restarts, and in extreme ambient temperatures, prevents a vapor lock condition. For additional information, please refer to the following topic(s): Engine Electrical, Engine Cooling Fan Thermal Switch.

     
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