You come home on a chilly wintry day and take off your coat, but it is freezing!  You walk over to the vent and put your hand up to it, and lukewarm air is being pushed out.  Why isn’t it blowing hot air?!  We all know that home repair can get expensive quickly, so in this article, we are going to walk you through some basic troubleshooting that you can do before calling in the cavalry.

Troubleshooting Checklist for A Furnace That Isn’t Blowing Hot Air

Check Your Pilot Light

One of the most common issues is the simplest: the pilot light is out.  The first thing to do is try and relight it.  If it stays lit, voila, problem solved!  If not, check the gas.  Do this by first seeing if the pilot light is dirty and if it is then clean it.  When it’s dirty it can prevent gas from flowing through the line smoothly.    Make sure that the gas valve leading to the furnace is set to on (running parallel to the line).

If you’ve tried these suggestions and your pilot will ignite but won’t stay lit, then there’s most likely an underlying problem with the thermocouple.  This means that it will need to be replaced or tinkered with.  This kind of repair can be above a lot of people’s handyman skill level, so if you’re uncomfortable please reach out to a professional or give us a call for more help!

Check Your Thermostat Settings

While your thermostat may have the heat on, check to see if the fan is set to ON rather than AUTO.  If the fan is set to ON, it will continue to blow constantly throughout the day regardless of whether or not the furnace is producing heat.

Check Your Air Filter

The typical symptoms caused by a clogged air filter are that the furnace blows hot, then cold air and then stops altogether.  If the air filter on a furnace is dirty it can prevent the free flow of air into the furnace.   This, in turn, can cause the furnace to run too long and overheat.  This will trigger a safety mechanism called a limit switch to turn the burners off and to blow cool air to lower its temperature.  Simply change out the air filter and see if the problem is resolved.

If this has been going on a long time and hasn’t been dealt with, or if the air filter has been changed but there are still issues, it could be a sign that there is underlying damage caused by the filter being dirty for too long.  If this is the case, we highly recommend that you give a professional a call to check out the issue.

Check the Flame Sensor

Another relatively easy fix is the flame sensor.  A good way to tell if this is your issue is if hot air initially starts blowing out and then becomes cold.  The sensor may need to be cleaned.  If it is dirty it could be taking inaccurate temperature readings that cause the temperature to be lowered.

Check the Ductwork

A less obvious potential cause of the cold air blues could be found in your attic!  It’s a possibility that there is a leak in the ducting that allows warm air to flow out and cold air to flow in, wasting all that precious heat on your attic space.  Another potential issue in the ducts could be dirt getting inside the air ducts which prevent consistent airflow.

You can clean these using a vacuum, toilet brush, screwdriver (to undo fasteners) and paper towels or microfiber cloths for dust.  You’ll want to cover the registers (those vents on the floor or ceiling), turn the fan on and shut off the heat/ac so that just the fan is running.  Then, you’ll want to make sure your filter is in place to catch the dust, loosen the dust with the toilet brush, and clean the registers with the vacuum and after, replace the furnace filter.  This is just a very basic cleaning so if you want to really get your hands dirty there are many resources available to you, or you can let our professionals do it for you!

Call Figlia & Sons for Fast Help with Your Furnace Not Blowing Hot Air

If you’ve gone through the troubleshooting gambit and still can’t resolve your heater’s issues, or if you just aren’t comfortable enough in your handyman skills yet, Figlia & Sons is here for you!

Having been around since 1960, we have the expertise and the experience to help you with any HVAC installation, PTAC repair, window unit repairs, and other HVAC services. With experience in various industries including residential condos, management companies, real estate development, healthcare facilities, hotels and more, we provide some of the fastest, most reliable service in NYC. Contact us today by filling out our online contact form or give us a call at 212-686-0094.

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