Heater fan stays on

Tiny
PGSWITZER
  • MEMBER
  • 2005 DODGE CARAVAN
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 195,000 MILES
Heater fan stays on when turned off one speed.
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Monday, October 8th, 2018 AT 7:52 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi and thanks for using 2CarPros.com.

If I understand, only one speed works and you can't shut the fan. If that is correct, I suspect that blower motor relay may be bad and shorted.

Here are the directions for removal and replacement. Make sure to allow the battery to be disconnected for approximately thirtyminutes prior to working on the vehicle. The attached picture shows the location of the resister. It will be under the dash, (behind the glove box).

REMOVAL

WARNING:
- On vehicles equipped with airbags, disable the airbag system before attempting any steering wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the negative battery (ground) cable, then wait two minutes for the airbag system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the air-bag system. Failure to take the proper precautions could result in accidental airbag deployment and possible personal injury or death.
- the blower motor resistor may get very hot during normal operation. If the blower motor was turned on prior to servicing the blower motor resistor, wait five minutes to allow the blower motor resistors to cool before performing diagnosis or service. Failure to take this precaution can result in possible personal injury.

CAUTION: Do not operate the blower motor with the blower motor resistor removed from the circuit. Failure to take this precaution can result in vehicle damage.

1. Disconnect and isolate the negative battery cable.
2. Remove the glove box from the instrument panel.

Blower Motor Resistor
3. Disconnect the two wire harness connectors from the front blower motor resistor.
4. Remove the two screws that secure the front blower motor resistor to the front HVAC housing and remove the resistor.

INSTALLATION
1. Position the front blower motor resistor into the front HVAC housing.
2. Install the two screws that secure the front blower motor resistor to the front HVAC housing. Tighten the screws to 2 N.m (17 in. lbs.).
3. Connect the two wire connectors to the front blower motor resistor.
4. Install the glove box.
5. Reconnect the negative battery cable.
__________________________

To check the resister, you will need to check for continuity between each of the pins. Here are the directions:

1. Disconnect and isolate the negative battery cable.
2. Disconnect the wire harness connector from the blower motor resistor.
3. Using an ohmmeter, check for continuity between all of the blower motor resistor terminals. In each case there should be continuity. If OK, repair the wire harness circuits between the blower motor switch and the blower motor resistor or blower motor as required. If not OK, replace the faulty blower motor resistor.

________________________________________

Here is a link that discusses using a multi-meter, which will be needed to check continuity. Additionally, inspect the wiring and plug. I have also attached a link for that type of check.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

If you find the resister to be good, then we need to check the blower motor relay. The blower motor relay is located next to the battery, under the hood, in the power distribution box. See the attached picture. Disconnect the negative battery terminal. Remove the relay in question. If there is another relay in the box that has the same part number, switch them and see if that makes a difference. Also, make sure the connections in the box are clean and not corroded or damaged by heat. Here is a link that shows how to check a relay if you need it.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Once you do these two things, the only thing left is wiring to and from the switch. That can get involved, but I'm willing to help if you want to dive into it. Just let me know.

Let me know what you find or if you have other questions.

Take care,
Joe
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Tuesday, October 9th, 2018 AT 6:01 PM

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