Why Is My Heater Not Working and What Can I Do?

Handyman replaces the filter in the hot air furnace at a home

Regular maintenance can help you avoid many common problems, but there are other issues that can prevent your heater from working. In some cases, it may be a simple fix. Today, we’ll show you some common reasons for why heaters malfunction and walk you through some simple DIY fixes.

Common reasons for heaters not working

Some of the most common problems with heaters include:

  • Wrong thermostat settings
  • Closed or blocked vents
  • Low or dead thermostat batteries
  • Dirty air filters
  • Leaking ductwork
  • Broken thermostat

Quick tips for when your heater isn’t working

Before you start taking things apart or calling for a professional, make sure that you check for the three most common reasons for heaters not working.

  1. Wrong thermostat settings: The most common problem with heaters is having the wrong settings. Is your thermostat set to heat? Is the fan set to on or auto? Check this first, then raise the temperature by 5 degrees. If after 5–10 minutes you don’t notice it getting warmer, check the next common but overlooked problem.
  2. Closed or blocked vents: It’s easy to forget that you closed your vents. It can be easy to accidentally close them, while tossing your shoes on the floor next to a vent, for example. You may also find clothes, furniture or even pets covering the vents and soaking up all the heat. Double-check that your vents are open and unblocked.
  3. Low or dead thermostat batteries: If you have a digital thermostat, check the display. If there’s a low-battery warning or the display is off entirely, replace the batteries. Refer to your owner’s manual for how to change the batteries in your specific thermostat. You should consider changing thermostat batteries once a year.

If these fixes don’t solve it, you might have dirty air filters.

Replacing dirty air filters

Generally, you should replace your air filter(s) every 1–3 months. You should also consider logging the last time you replaced them. If your heater isn’t working and you have dirty air filters, follow these steps to replace them. (Make sure you know the correct filter size to use. You can find out by locating where your filter is housed and checking the size of the filter in the housing.)

  1. Turn off your furnace and remove any filter housing covers.
  2. On the old filter, look for a little arrow. This indicates the direction of airflow. You’ll want to install the new filter with the arrow facing in the correct direction.
  3. Remove the old filter.
  4. Take any plastic covering off the new filter. Slide the new filter in place with the arrow facing in the appropriate direction.
  5. Replace any filter housing covers and write down the date of change.

This may solve the problem of your heater not working.

I’ve tried these tips and I’m still cold

If none of these tips resolve your issue, the problem may be a bit more complex and require professional service, which can be pricey and time consuming. This is why many homeowners choose to purchase a Home Warranty Service Agreement from 2-10 Home Buyers Warranty (2-10 HBW) before things go wrong.

With a Home Warranty Service Agreement from 2-10 HBW, you can request service for routine wear and tear on your furnace and have a qualified, approved service contractor assess your issue. This can save you time, money and the grief of repairing or replacing a major system or appliance entirely out of pocket.

2-10 HBW offers the most comprehensive home warranty coverage for homeowners. Let us help you protect your home.


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