Dakota, 2001-2005

Electric Engine Fan

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Fan Switch



Operation

Vehicles equipped with the 2.5L engine use an electric fan for engine cooling. Models with the 3.7L and 4.7L engines incorporate an auxiliary electric fan to aid low-speed cooling. Fan operation is controlled by the PCM through a relay located in the Power Distribution Center (PDC). The PDC is in the engine compartment on the left fender inner shield. The location of the fan relay is given on the inside of the PDC cover.

The fan relies upon several inputs to determine operation, notably the coolant temperature sensor .



The fan will run whenever the engine is running and the air conditioner compressor clutch is engaged.
 
When the air conditioner compressor clutch is disengaged, the fan will run at vehicle speeds above 40 mph if coolant temperature is above 230°F (110°C). The same is true of vehicles without air conditioning.
 
The fan will turn off when coolant temperature drops to 220°F (104°C).
 
At speeds below 40 mph, the fan turns on when coolant temperature reaches 210°F (99°C) and turns off when coolant temperature drops to 200°F (93°C).
 
The fan will not run during engine cranking.
 

Testing
  1. If the fan will not run, the easiest test is to disconnect the fan motor lead and apply 12v across the connector. Note polarity as shown in the illustration. If the fan runs, the problem is in the circuit or upstream components.
  2.  
  3. With the ignition and air conditioner ON , check for voltage across the wiring harness side of the fan motor connector. Note polarity as shown in the illustration. There should be 12v at the connector. If there is, the problem is the fan motor. If not, suspect the relay, circuitry, or other upstream component.
  4.  
  5. The PCM will set a diagnostic trouble code in the memory if it detects a problem in the fan relay or circuit, although a DRB scan tool is required for this analysis. If not available, proceed as follows:
  6.  
  7. Check fuses: there is a 10A fuse in the junction block and a 40A maxi fuse in the PDC.
  8.  
  9. Locate the fan relay in the PDC (location is shown on the cover). Apply 12v (with 14-gauge wire) to relay terminal 87. If the fan will not run, check for an open circuit in C25 or Z1. If the circuits are okay, replace the fan.
  10.  
  11. With the ignition key OFF , check for battery voltage at circuit C28 (relay terminal 30). If no battery voltage is present, check for open/short circuit C28 between the PDC and relay.
  12.  
  13. With the ignition key in the RUN position, check for battery voltage at circuit F18 (relay terminal 86). If no battery voltage is present, check for an open/short in circuit F18 between the junction block and the relay.

    Click image to see an enlarged view

    Fig. Note fan polarity before testing

  14.  

Removal & Installation




CAUTION
If the fan blade is bent, warped, cracked or damaged in any way, it must be replaced only with a replacement fan blade. Do not attempt to repair a damaged fan blade.

  1. Disconnect battery negative cable.
  2.  
  3. Disconnect fan motor wire connector.
  4.  
  5. Remove the two fan shroud mounting clips connecting the upper part of fan shroud to the radiator.
  6.  
  7. Remove fan assembly from radiator.
  8.  

To install:

  1. Install fan assembly onto the radiator. Tighten bolts 5 Nm (45 in. lbs.).
  2.  
  3. Connect fan motor wire connector to harness connector.
  4.  
  5. Connect battery negative cable.
  6.  
  7. Start engine and check fan operation.
  8.  


WARNING
If the viscous fan drive is replaced because of mechanical damage, the cooling fan blades should also be inspected. Inspect for fatigue cracks, loose blades, or loose rivets that could have resulted from excessive vibration. Replace fan blade assembly if any of these conditions are found. Also inspect water pump bearing and shaft assembly for any related damage due to a viscous fan drive malfunction.


NOTE
Gasoline engine fans have a standard RIGHT-HAND thread. Turn CCW to loosen.

  1. Disconnect the battery negative cable(s).
  2.  
  3. Disconnect the throttle cable if attached to the fan shroud.
  4.  
  5. Remove the windshield washer bottle and coolant overflow tank from the fan shroud.
  6.  
  7. Stop the water pump from turning with a special tool or prybar on the nuts. Loosen the fan nut (36mm). Turn CCW to loosen.
  8.  
  9. Remove the fan shroud mounting hardware. These may be bolts, clips or a combination of the two, depending on model.
  10.  
  11. Remove the fan and shroud together.
    WARNING
    Store the fan in the vertical (operating) position. If placed on its side, the silicone fluid in the viscous drive could drain into the bearing assembly and contaminate the lubricant.

  12.  
  13. To replace the fan or viscous drive, remove the four bolts and separate the components.
  14.  

To install:

  1. If drive and fan were separated, tighten the bolts to 17 ft. lbs. (23 Nm).
  2.  
  3. The remainder of the installation procedure is the reverse of removal.
  4.  
  5. If a new viscous drive has been fitted, start and run the engine at 2,000 rpm for about 2 minutes to distribute fluid within the drive.
  6.  

 
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