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2 Possible Reasons Why Your Home's Furnace Refuses To Stay On

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After realizing that your home is not staying warm, you may have found that the furnace is not running. Even if you do manage to get it to turn on, it might almost immediately switch off, leaving you to wonder what is causing the issue.

If you have checked the circuit breaker and the thermostat and haven't found problems with either, the problem is most likely within the heating system itself. Below are a couple of possible reasons why your home's furnace refuses to stay on and may need the attention of a professional.

1. Air Filter Is So Clogged up It Is Blocking the Airflow Through the System 

One possible reason why your furnace might keep shutting off as soon as it comes on is if the airflow is blocked. If it has been a while since the filter has been changed, or if you have recently done some deep cleaning in your home, it may be completely clogged up.

If this is the case, the lack of airflow is sending a signal to the furnace to immediately shut down because there is a problem. Even if you change the dirty filter, there could still be excessive dust and dirt within the furnace caused by the blockage. In this case, you need to have a professional clean out the unit to restore the flow of air.

2. Furnace's Fail-safe System Is Being Triggered by a Faulty Ignition Switch

Another possible reason why the furnace either is not coming on or switching off immediately is that it has a faulty ignition switch. When this switch is no longer heating up, it triggers the fail-safe system and shuts down the furnace to keep electrical issues from arising.

When the furnace is actually running, feel the air to see if it is warming up at all. If not, the ignition switch is most likely to blame and will need to be replaced by a professional.

If your furnace does not turn on or does come on only to immediately shut off again, the airflow may be blocked by a clogged air filter. If you have checked the filter or have recently replaced it, the next possible culprit is a faulty ignition switch that is triggering the furnace's fail-safe system. If you suspect that this is the case or cannot determine what is causing the issue, contact an HVAC contractor who offers heating services to have them handle the problem for you.