When Your Furnace Comes on but No Heat Comes out of Your Vents


When Your Furnace Comes on but No Heat Comes out of Your Vents

When winter hits and the temperatures drop, the last thing you want is a furnace that seems to be working, but isn’t actually blowing hot air through the vents. Fortunately, the cause may be simpler than you think and you may be able to fix the problem yourself. Follow these troubleshooting tips to figure out why heat isn’t coming out of your vents:

Take a Look at the Thermostat

There should be a switch for the fan near the bottom of your thermostat. The switch has two settings: ON and AUTO. When the fan in the on position, it will constantly blow air through the home. This means that you may feel cold air coming from the vents. When you place the switch in the auto position, the fan will only activate when the air has been heated to the correct temperature. Make sure the thermostat’s fan switch is on auto in order to prevent cool air from being fed into your home.

Check the Air Filter

Can’t remember the last time you changed your furnace’s air filter? If so, there is a good chance that the filter is too dirty to allow the furnace to work properly. A dirty air filter can interrupt the air flow over the heat exchanger and cause it to overheat. At this point, the high limit switch will be tripped for safety reasons and the burners will be shut off. Be sure to change your air filter every month to improve indoor air quality and prevent furnace problems.

For Fast & Affordable Furnace Repair

Inspect the Pilot Light

Older furnaces rely on a standing pilot light to operate. Sometimes the pilot light can be snuffed out and will need to be relit so that the burners can produce heat. If you don’t see a blue flame near the bottom of your furnace, you will need to access the reset switch and use a lighter to light the pilot again.

Check the Condensate Line

Newer, high efficiency furnaces create water when they operate. This excess moisture is then emptied through a drain line. If the line becomes blocked, the water will end up back in the furnace, which will trip the overflow kill switch and shut down your furnace. Pooling water around the furnace is a good sign that the condensate line is blocked and will need to be cleaned.

Inspect Your Air Ducts

The problem may not be your furnace. Leaky ducts in your home can cause heated air to escape and result in cooler and weaker air flow through the vents. This can impact your home’s energy efficiency and force your furnace to work overtime. Not only won’t your home ever get as warm as you would like, you will end up having to replace your furnace sooner than expected. It is important to seal up any leaks or gaps so that hot air is directed into the home. 

Make Sure Heat Registers are Open

You probably don’t pay much attention to your heat registers, which makes it hard to notice when they accidentally get closed. This is all too common, especially in a home with small children who love to play with just about anything. Before you call in a professional to inspect your furnace, make sure that all the registers are fully open and not being blocked by any furniture.

Hit the Reset Button

Many furnaces come with a red reset button. Hitting the button can be enough to get your furnace back up and working properly. However, if you find yourself having to push the reset button pretty frequently, you will want to get to the root of the problem and figure out why the automatic shut off feature is being triggered. 

In many cases, cold air blowing through your vents is an easy problem to fix that you can do yourself. If none of the troubleshooting steps listed above help address the problem, it is time to call a professional and have an HVAC expert diagnose your furnace problems.

Schedule Home Furnace Repair Today

If you suspect that you are experiencing any of the common home furnace problems above, please don’t hesitate to give us a call.  We can have a certified service technician at your home as quickly as possible to fix any issues behind your furnace not heating properly.  To set up your home furnace repair today, call our office at (314) 209-7500 or fill out the online form below.

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