Heating System Session 7: Troubleshooting

An understanding of the specific sequence used by the furnace is critical to troubleshooting a furnace that is not working or insufficiently heating. Once the thermostat calls for heat, the blower motor starts, lifting the sail switch to tell the module board there is enough air flow. Then the burner assembly lights and provides heat. Many RV owners bypass this step in troubleshooting and think that if the blower is running, the module board must be bad.