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3 Potential Reasons Your Furnace Is Blowing Out Lukewarm Air

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Has your furnace suddenly become inefficient to the point that all you can receive is lukewarm air regardless of the thermostat setting? There are a few potential reasons for the sudden downgrade in your unit's heating ability. Most of the fixes will involve the help of a furnace repair technician, but understanding the origin of the problem can help you explain the problem over the phone and better interact with your system in the future.

Here are three potential reasons your furnace is blowing out lukewarm air.

Thermostat Issue

The solution to a seemingly major problem is often simple. Thermostat issues are a common cause of furnaces seeming to underperform when there's actually nothing wrong with the system itself.

First, check to make sure you've changed the batteries in the thermostat recently. If you haven't, do so now. Dying batteries can cause a thermostat to malfunction and send the furnace improper signals before you ever see problems with the display.

Next, make sure the thermostat settings are correct. Set the system to auto so that the entire unit will turn off when your desired temperature is reached. Another setting could leave the fan running when the furnace kicks off, which can make it seem like lukewarm air is coming out of your vents.

Air Filter Clogging or Improperly Installed

The furnace air filter is a line of defense that removes particulates from the air so you have a dust-free heating experience. The air filter needs to be either cleaned or replaced periodically, with the method of cleaning and the frequency varying depending on furnace model. Consult your owner's manual for detailed instructions. Failure to change the air filter in a timely fashion can lead to the air filter becoming clogged and blocking some of the hot air from getting through to your home, which causes the lukewarm air. 

You also need to make sure that you didn't accidentally put the air filter in backwards during your last cleaning or replacement. The improper positioning can lead to blocked air even though the filter is technically clean.

Flame Sensor Issue

Do you have a gas furnace that's putting out lukewarm air but you know the pilot light is staying lit properly? The unit could have a problem with its flame sensor, which is the part that checks to see that the pilot is on and then signals the supply of gas that powers the unit. If the sensor is faulty, it can think the pilot has gone out even when it stays lit and prematurely cut your gas supply.

For more information, contact an HVAC service, such as Greers Service Company Inc.