1. Understanding the System:
Before diving into parts, understand that your heater system likely has:
* Heater Core: This is where the hot coolant from the engine heats the air.
* Blower Motor: This blows air across the heater core. You have one for the rear (which works) and likely one for the front (which doesn't).
* Blend Doors: These are flaps that control the direction of airflow (front, rear, defrost, etc.). They're controlled by actuators.
* Actuators: These are small motors that move the blend doors.
* Control Panel: This is where you select the temperature and airflow direction.
* Relays: These are electrical switches that control power to components like the blower motors.
* Wiring: Connects all the components.
2. Locating Components:
* Blower Motors: These are usually located behind the dashboard (front) and under the rear seating area (rear, likely near the floor). Accessing them might require partial disassembly of the dashboard or removal of seats/trim panels.
* Relays: These are typically found in a fuse box, often under the hood or inside the vehicle, sometimes in a separate relay center. Your owner's manual should show the location and identify relays associated with the heating/AC system. Look for relays labeled "blower motor" or similar.
* Actuators: These are usually located within the ductwork under the dash, making them difficult to access. You may need to remove parts of the dash to find them.
* Control Panel: This is on your dashboard, the main control for the climate system.
3. Troubleshooting Steps:
1. Check the Obvious: Ensure the front blower motor is getting power. Check the fuse(s) for the front blower motor in the fuse box. If the fuse is blown, replace it with one of the same rating. If it blows immediately again, there's a short circuit somewhere.
2. Listen for the Blower Motor: With the front blower switched on, listen carefully near the dash. Can you hear a faint whirring? If not, the motor may be bad or not receiving power.
3. Test the Front Blower Motor Directly (Advanced): This requires electrical knowledge and caution! Disconnect the blower motor's electrical connector. Using a test light or multimeter, check for 12V power at the connector when the blower is switched on. If power is present, the motor is likely faulty. If no power, check the wiring for continuity back to the relay and control panel.
4. Check the Relays: If you've got power at the motor connector, the next step is to check the relays themselves. You can sometimes hear them click when activated. Swap the front blower relay with a similar-looking relay (perhaps one that controls something else that works—*only if they have the same amperage rating*). If the problem switches to the other component, you've found a bad relay.
5. Inspect the Blend Doors/Actuators (Advanced): This requires removing parts of the dashboard and is best done with a repair manual. You'll want to check if the blend doors are moving correctly when you change the airflow settings. If they're stuck, the actuator may be faulty.
6. Wiring Inspection (Advanced): Trace the wiring from the control panel to the front blower motor, checking for breaks, corrosion, or loose connections. This is the most time-consuming and difficult step.
4. Resources:
* Repair Manual: A Haynes or Chilton repair manual for your 1995 Nissan G20 is invaluable. It will provide diagrams, component locations, and troubleshooting guides.
* Online Forums: Search online forums specific to Nissan G20s or conversion vans. Other owners might have experienced the same issue.
Important Safety Notes:
* Disconnect the battery's negative terminal before working on any electrical components.
* Do not work on the electrical system if you're not comfortable with basic automotive electrical principles. Incorrect wiring can damage components or even cause a fire.
* Consult a qualified mechanic if you're unsure about any step. Improper repairs can lead to more serious problems.
Finding and replacing relays and motors is relatively straightforward once you locate them (though accessing them may be tricky). However, diagnosing the *cause* of the problem might require more advanced troubleshooting, especially if it involves blend doors or wiring. A repair manual will be your best friend in this process.
