1. Power and Ground Checks:
* Fuse: Check the fuse(s) related to the blower motor. Your owner's manual will show the fuse box layout and which fuse(s) control the blower. A blown fuse is a simple, cheap fix.
* Power at the Blower Motor Connector: With the ignition ON, use a multimeter to check for power at the connector going to the blower motor. You should have battery voltage (12V) on one wire when the blower switch is activated. If not, the problem is upstream of the motor.
* Ground Connection: Ensure the blower motor has a good ground connection. A poor ground can prevent the motor from working even if it receives power. Clean the ground connection and ensure it's making good contact.
2. Blower Motor Switch and Wiring:
* Switch Testing: The blower motor switch itself could be faulty. You can try testing the switch's continuity with a multimeter (following a wiring diagram for your van's model). This requires more advanced electrical knowledge. If you're not comfortable doing this, a mechanic can easily test this.
* Wiring Harness Inspection: Carefully examine the wiring harness leading to the blower motor and the switch. Look for any broken, frayed, or corroded wires. Repair or replace any damaged wiring. Pay close attention to the connections.
3. Body Control Module (BCM) or Related Control Modules:
* BCM/Control Module Involvement: On newer vehicles, the blower motor is often controlled by a Body Control Module (BCM) or a similar control module. A malfunctioning BCM could be preventing the blower from receiving power. Diagnosis of a BCM issue usually requires specialized tools and knowledge.
4. Other Possibilities:
* Incorrect Blower Motor Installation: Double-check that you installed the blower motor correctly, especially if it was removed during previous maintenance.
* Other Relays: There might be other relays involved in the blower motor circuit, besides the resistor relay, which could have failed. Your repair manual will show a wiring diagram of the circuit.
Important Considerations:
* Wiring Diagram: Obtain a wiring diagram for your specific 2000 Dodge 3500 van. This diagram will be invaluable in tracing the electrical path and identifying all components involved. A Haynes or Chilton manual, or online resources may have this.
* Safety: Disconnect the negative battery terminal before performing any electrical testing or repairs.
* Professional Help: If you're not comfortable working with automotive electrical systems, it's best to take your van to a qualified mechanic for diagnosis and repair. Troubleshooting electrical issues can be tricky and require specialized tools.
By systematically checking these areas, you should be able to pinpoint the cause of the blower motor failure. Remember to consult a wiring diagram for your specific vehicle model to accurately identify wires and components.
