Troubleshooting Gas Furnaces and Gas Heaters
There are many potential reasons that a furnace might not be working, but fortunately, many of the solutions are as easy as pressing a button. Use this chart to fix a wide range of conditions that prevent your furnace from working.GAS AND FURNACE HEATER TROUBLESHOOTING CHART
| Problem | Possible cause | Solution | ||
| Furnace won't run |
1. No power. |
| ||
| 2. Switch off. |
2. Turn on separate power switch on or near furnace | |||
| 3. Motor overload. |
3. Wait 30 minutes; press reset button. Repeat if necessary. | |||
| 4. Pilot light out. |
4. Relight pilot. | |||
| 5. No gas. |
5. Make sure gas valve to furnace is fully open | |||
| Not enough heat |
1. Thermostat set too low. |
1. Raise thermostat setting 5°. | ||
| 2. Filter dirty. |
2. Clean or replace filter. | |||
| 3. Blower clogged. |
3. Clean blower assembly. | |||
| 4. Registers closed or blocked. |
4. Make sure all registers are open; make sure they are not blocked by tugs, drapes or furniture. | |||
| 5. System out of balance. |
5. Balance system. | |||
| 6. Blower belt loose or broken. |
6. Adjust or replace belt. | |||
| 7. Burner dirty. | 7. Call a professional. | |||
| Pilot won't light |
1. Pilot opening blocked. |
1. Clean pilot opening. | ||
| 2. No gas. |
2. Make sure pilot light button is fully depressed; make sure gas valve to furnace is fully open. | |||
| Pilot won't stay lit |
1. Loose or faulty thermocouple. |
1. Tighten thermocouple nut slightly, if no results, replace thermocouple. | ||
| 2. Pilot flame set too low. |
2. Adjust pilot so flame is about 2 inches long. | |||
| 3. Electric pilot faulty. |
3. Call a professional. | |||
| Furnace turns on and off repeatedly |
1. Filter dirty. 2. Motor and/or blower needs lubrication. |
1. Clean or replace filter. 2. If motor and blower have oil ports, lubricate. | ||
| Blower won't stop running |
1. Blower control set wrong. |
1. Reset thermostat from ON to AUTO. | ||
| 2. Limit switch set wrong. |
2. Reset limit switch for stop-start cycling. | |||
| 3. Limit control needs adjustment. |
3. Call a professional. | |||
| Furnace noisy |
1. Access panels loose. |
1. Mount and fasten access panels correctly. | ||
| 2. Belts sticking, worn, or damaged. |
2. Spray squeaking drive belts with belt dressing; replace worn or damaged belts. | |||
| 3. Blower belts too loose or too tight. |
3. Adjust belt. | |||
| 4. Motor and/or blower needs lubrication. |
4. If motor and blower have oil ports, lubricate. | |||
|
5. Call a professional. |
The pilot light is crucial to the operation of the furnace. Learn how to light a pilot light on the next pae.
For more articles on home repair, check out the following links.
- Furnace Maintenance: Save yourself time and money by learning the steps to keep your furnace in prime condition.
- Major Appliance Repair: If the furnace isn't the only thing in your house on the fritz, you can learn how to fix other machines in this article.
- Small Appliance Repair: Once you've tackled the furnace, a toaster or blender seems like child's play. Find out how to fix them here.
- Thermostat Maintenance: To make sure there's actually a problem with your heating system, you may want to check the thermostat, too. Learn how to calibrate a thermostat.
