Here's a more systematic approach:
1. Check the obvious: Make sure the heater control is set to "Hot" and the fan is on. Sometimes the problem is as simple as accidentally turning the heater off.
2. Listen for the blower motor: With the fan on, listen carefully near the heater vents. Do you hear the blower motor running? If not, the problem might be with the motor itself, not the fuse.
3. Locate the heater fuse: Consult your 1991 Chevrolet Lumina's owner's manual. It will have a fuse box diagram showing which fuse controls the heater blower motor. The fuse box location will vary, it's usually under the hood or under the dash. The manual will also list the amperage of the fuse.
4. Inspect the fuse: Once you've located the correct fuse, carefully remove it and inspect it. Look for a broken filament (a thin wire inside the fuse) or a burnt appearance. If the fuse is blown, it will appear visibly damaged.
5. Replace the fuse (if necessary): If the fuse is blown, replace it with a fuse of the same amperage. Using a higher amperage fuse is dangerous and could cause a fire. Do not use a makeshift replacement.
6. Test the heater: After replacing the fuse, turn the heater on again. If it still only blows cold air, the problem is likely *not* a blown fuse.
If replacing the fuse doesn't solve the problem, the issue could be one of the following:
* Blower motor resistor: This component controls the fan speed. A faulty resistor can prevent the fan from working or limit it to only one speed.
* Blower motor itself: The motor may be worn out or have failed completely.
* Heater core: This is a radiator-like component that heats the air. A clogged or leaking heater core will result in cold air.
* Thermostat: A faulty thermostat might prevent coolant from reaching the heater core.
* Low coolant level: Check your coolant level – if it's low, your heater won't work properly.
* Wiring issues: A broken wire or faulty connection in the heater circuit could be the culprit.
If replacing the fuse doesn't fix the problem, you'll need to further diagnose the issue, possibly with a multimeter to check voltage and continuity, or by seeking professional help from a mechanic. Attempting repairs beyond replacing a fuse requires some electrical knowledge and the right tools.
