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Common Issues When Your Gas Furnace Won’t Start
Dealing with a gas furnace that won’t start can be frustrating, especially during cold winter months. However,
there are common issues that can cause this problem. Let’s explore a few possibilities:
1. Thermostat Malfunction
The thermostat is the first component you should check when your gas furnace won’t start. Make sure it’s set to
the desired temperature and functioning properly. You might also want to replace the thermostat batteries if
2. Lack of Power
Gas furnaces require electricity to operate certain components. If the furnace doesn’t receive power due to a
tripped circuit breaker or a blown fuse, it won’t start. Check the circuit breaker panel and ensure everything
is in order.
3. Ignition or Pilot Light Issues
If your gas furnace uses an electronic ignition system, a faulty ignition might be preventing it from starting.
Alternatively, if you have an older furnace with a pilot light, ensure the pilot light is ignited. A
malfunctioning ignition or a pilot light that won’t stay lit can be the source of the problem.
4. Gas Supply Problems
A gas furnace that won’t start might be experiencing issues with the gas supply. Check if your gas service is
active and if the gas valve is turned on. Additionally, inspect the gas line for any leaks or damage that may
prevent proper fuel flow.
5. Dirty Air Filters
Clogged or dirty air filters can restrict airflow and cause your gas furnace to malfunction. Replace or clean
the air filters regularly to prevent such issues. These filters are usually located near the blower motor or
inside the return air grille.
6. Faulty Safety Switches
Your gas furnace has several safety switches that are designed to protect against potential hazards. If any of
these switches, such as the pressure switch or the flame rollout switch, are faulty or triggered, the furnace
won’t start. Consult a professional technician to diagnose and fix the problem.
When to Call a Professional
If you have tried troubleshooting the above issues and your gas furnace still won’t start, it’s recommended to
call a professional HVAC technician. They have the knowledge and expertise to diagnose and repair complex
problems that may be beyond the scope of a typical homeowner.
If your gas furnace won’t start, it’s essential to identify and address the underlying issue promptly. By
checking the thermostat, power supply, ignition system, gas supply, air filters, and safety switches, you can
often resolve the problem yourself. However, if troubleshooting doesn’t work, it’s wise to seek professional
assistance. Remember, a well-maintained furnace not only ensures your comfort but also improves energy
efficiency and prolongs the lifespan of your heating system.