1. Power Supply:
* Fuse: Check the fuse(s) related to the blower motor. Your owner's manual will show you the fuse box location and the appropriate fuse(s). Visually inspect for a blown fuse (broken filament).
* Relay: The blower motor likely uses a relay. This is an electrically controlled switch. A faulty relay can prevent power from reaching the motor. You'll need to locate the relay (often in the underhood fuse box) and either test it with a multimeter or swap it with a known good relay of the same amperage.
* Wiring: Inspect the wiring harness leading to the blower motor for any breaks, chafing, or corrosion. This is particularly important where the wires enter the blower motor housing. A visual inspection might be enough, but a multimeter can confirm continuity.
* Blower Motor Resistor: This component controls the different fan speeds. A faulty resistor can cause the blower to not work on any speed or only on the highest speed. These are often located behind the glove box or under the dash.
2. Blower Motor:
* Motor Failure: The blower motor itself could have failed. This is often due to wear and tear or a seized bearing. You might hear a clicking or humming sound if the motor is struggling to start. Testing the motor directly with power (carefully!) can confirm if it's functional.
* Switch Failure: The blower motor switch (the control on the dash) could be faulty. It's possible the switch itself is broken or the wiring to the switch is bad.
3. Other Factors:
* Vacuum Leaks: While less common, some vehicles use vacuum lines to control the heater blend door. If the vacuum system has leaks, it might prevent the heater from functioning properly, even if the blower is working.
* Low Coolant: If your coolant level is low, the heater core might not be getting enough hot coolant to effectively heat the air.
Troubleshooting Steps:
1. Start with the simplest: Check the fuses first.
2. Visually inspect: Look for obvious problems in the wiring.
3. Test with a multimeter: This is the best way to definitively diagnose problems with the fuses, relay, wiring, and motor.
4. Access the blower motor resistor: This is often a common point of failure.
5. Check the blower motor switch: Try switching through different speeds to see if you can isolate the problem.
6. Consult a repair manual: A shop manual specific to your 1996 Ford Explorer will be invaluable in providing diagrams and detailed troubleshooting steps.
If you're not comfortable working with electricity, it's best to take your Explorer to a qualified mechanic. Attempting electrical repairs without proper knowledge can be dangerous.
