1. Turn off the power to the furnace at the circuit breaker or fuse box.
2. Remove the access panel to the furnace.
3. Locate the gas valve.
4. Check the polarity of the wires connected to the gas valve. The positive wire should be connected to the positive terminal on the valve, and the negative wire should be connected to the negative terminal.
5. If the wires are connected incorrectly, reverse them.
6. Replace the access panel to the furnace.
7. Turn on the power to the furnace at the circuit breaker or fuse box.
8. Test the furnace to ensure it is working properly.
