1. Check the Fuses and Relays:
* Locate the fuse box(es): Your Jeep likely has multiple fuse boxes – one under the hood and potentially one inside the cabin (often under the dash). Consult your owner's manual for their exact locations and diagrams.
* Identify the relevant fuses and relays: Look for fuses and relays related to the blower motor, HVAC system, or similar. The manual should show which fuse and relay control the blower motor. They might be labeled "blower motor," "HVAC," or something similar.
* Inspect visually: Check for blown fuses (a broken filament inside) and any signs of damage to the relays (burned contacts, etc.). Replace any blown fuses with the correct amperage. If a relay looks suspect, it's best to replace it as well.
2. Test the Blower Motor Resistor:
The blower motor resistor controls the fan speeds. A faulty resistor can cause the blower to stop working altogether.
* Locate the resistor: This is usually located behind the glove box or under the dash, often near the blower motor itself. Access may require removing the glove box or some trim panels. Your repair manual will help pinpoint its location.
* Inspect visually: Check for any signs of burning or damage.
* Test for continuity: If you have a multimeter, you can test the resistor for continuity (a complete electrical circuit) at each speed setting. A lack of continuity indicates a faulty resistor, requiring replacement.
3. Check the Blower Motor Itself:
The blower motor might be the problem.
* Access the blower motor: This usually involves removing parts of the dash or HVAC system. Again, your repair manual is critical here.
* Test the motor: With the power disconnected, you can test the motor's windings for continuity using a multimeter. Lack of continuity usually means a bad motor. You can also try manually spinning the blower motor shaft; it should spin freely without resistance. If it's seized up, it's likely failed.
* Check the wiring: While you have access to the motor, inspect the wiring harness connected to it for any broken or loose wires, corrosion, or damaged connectors.
4. Check the Blower Motor Switch:
The switch that controls fan speed could be faulty, causing no power to reach the motor. This is less likely if *both* AC and heater are affected, as this would often only affect the speed selection, not the complete lack of function.
5. Power Supply:
If you've checked all the above and still have no blower function, there's a chance the problem lies in the main power supply to the blower system itself. This could involve more extensive electrical diagnostics to identify short circuits or other faults in the wiring harness.
Important Notes:
* Repair Manual: A repair manual specific to your 1996 Jeep Grand Cherokee is highly recommended. It will provide detailed diagrams, locations of components, and troubleshooting steps.
* Safety: Disconnect the battery negative terminal before working on any electrical components to prevent short circuits or shocks.
* Professional Help: If you're not comfortable working on your vehicle's electrical system, it's best to take it to a qualified mechanic. Improper repairs can lead to further damage.
By systematically checking these areas, you should be able to pinpoint the source of the problem with your Jeep's blower motor. Remember to always consult your repair manual for specific details and diagrams relevant to your vehicle.
