Why Won't My Furnace Start?

If your furnace won't start, it may be due to several problems. Some are serious, while others aren't, but it's always a good idea to call a heating contractor for a furnace repair just in case.

Furnace Door Safety Switch

Your furnace door has a safety switch that keeps it from turning on when the door is open. If someone recently opened it to change filters or perform maintenance, it may not have been closed properly.

If you try opening and closing the door and the safety switch still won't engage, the switch has likely failed. You will need a heating contractor to replace it.

Faulty Flame Sensor

A flame sensor is used to detect whether a pilot light is lit inside a gas appliance. If it detects that the pilot light is not lit, then it will turn off the gas supply to prevent gas leaks.

Since this sensor is near a constant flame, it's only natural for it to fail over time. The only solution is to replace it.

Blocked or Clogged Air Vents

You may have an air vent blocked due to placing furniture over it or clogged due to dust, leaves, or other debris. Another safety feature of your furnace is that it won't turn on when the air pressure isn't right.

In some cases, all you need to do is clean out your vents and make space around them. However, if debris has gotten deep inside of your system, it's better to get a professional cleaning. Debris can also jam up your furnace's components, so it's a good idea to get a professional inspection.

Pilot Light

The pilot light is a constant flame that helps a gas or oil furnace to ignite its main burner when it's time to turn on. This light can be accidentally put out on occasion, but frequent problems are a sign that it needs repair.

You may have air leaks in your furnace, or there could be debris that got into your system and started blocking the pilot light.

Furnace Ignition Switch

The ignition switch is similar to an electric lighter you'd use to start a grill. If you hear a clicking noise but your heat isn't coming on, that's often a sign of a failed ignition switch. There is nothing you can do to make your ignition switch work again. If it fails, it needs to be replaced.

To schedule your furnace repair, contact a local heating contractor today.