When cold weather hits, the last thing you want is a furnace that will not start. A faulty starting mechanism is a common issue many homeowners face, and it can be caused by a variety of problems, some simple, others more complex. Understanding what might be causing your furnace to fail at startup can help you troubleshoot or know when to call in a professional. LV Heating & Cooling would like to explore the most common causes of a faulty furnace starting mechanism and what you can do about them.
Malfunctioning Ignition System
Modern furnaces typically use either an electronic ignition or a hot surface igniter to start. Over time, these components can wear out or become dirty. If your igniter is not glowing or your furnace does not click to ignite, this may be the issue. No glow from the igniter, repeated clicking with no ignition, furnace blowing cold air indicates a problem. The igniter will need to be either clean or replace. A technician can test the component for continuity and replace it if needed.
Faulty Thermostat
Sometimes the problem is not with the furnace itself, but with the thermostat. If it is not communicating properly with the furnace or if the batteries are dead, your system won’t start. When the furnace does not respond to thermostat settings, screen is blank, or temperature readings seem off. The first is to replace batteries, recalibrate, or consider upgrading to a newer programmable or smart thermostat.
Blown Fuse or Tripped Circuit Breaker
Your furnace requires electricity to power components like the blower motor and ignition system. If a fuse has blown or the circuit breaker has tripped, your furnace will not start. A furnace is completely unresponsive, no sounds, no airflow, no ignition. Check your breaker panel and furnace switch. If the problem persists after resetting, contact a professional to inspect for underlying electrical issues.
Clogged Air Filter
A dirty air filter can restrict airflow and cause the furnace to overheat. When this happens, safety sensors may prevent the system from turning on to avoid damage. A clogged air filter may cause frequent cycling, poor airflow, furnace not starting at all. Replace the air filter every 1 to 3 months, depending on usage and filter type.
Dirty Flame Sensor
The flame sensor ensures the burners are producing a flame when the furnace starts. If the sensor is dirty or corroded, it may shut the system down because it can’t detect the flame. Signs of a dirty flame sensor is the furnace lights briefly then shuts off, or does not start at all. To correct this problem the flame sensor will need to be cleaned, a technician can replace it if necessary.
Pilot Light Issues
Older gas furnaces may use a standing pilot light. If this light goes out due to a draft or dirty thermocouple, the furnace will not start. When a pilot light has an issue there will be no flame in the pilot window, no ignition. First try to relight the pilot light following the manufacturer’s instructions. If it will not stay lit, the thermocouple may need replacement.
Pressure Switch Failure
The pressure switch ensures the inducer fan is working and that the venting is clear. If it doesn’t detect the right conditions, it will not allow the furnace to start. An error code on the control board, furnace doesn’t start or shuts down after a few seconds. This usually requires a professional diagnosis and replacement of the pressure switch or correction of venting issues.
Heating Inspections, Tune Ups, Repair, Replacement & More in Summerlin, North LV, Henderson, Enterprise, Paradise, Spring Valley, Sunrise Manor & Greater Las Vegas, NV
A furnace that will not start can lead to discomfort and even safety concerns in colder months. While some of these issues can be solved with basic troubleshooting, others require the experience and tools of a licensed HVAC technician. To prevent starting mechanism issues, be sure to schedule regular furnace maintenance each year before the cold season begins. For furnace repair services and more, contact LV Heating & Cooling today.
