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Why Isn’t My Furnace Blowing Air?

Serving Families Throughout Palm Springs
replacing an AC filter

Broken Furnace in Palm Desert?

It’s late November, and while it’s not exactly cold outside here in Palm Desert, it is starting to get pretty chilly at night. If homeowners haven’t turned their furnace on for the first time this year yet, the time is indeed coming. But what do homeowners do if the heater doesn’t work when they turn it on? Or if it’s blowing cold air instead of hot air? It’s stressful to call an HVAC technician to the home, especially when the family’s comfort is on the line. Here at Desert Air Conditioning, a customer’s comfort is crucial. Here is a furnace troubleshooting guide that details the common causes of that malfunctioning furnace and what to do about them:

Furnace Troubleshooting Guide

To better troubleshoot what might be wrong with a furnace that’s not blowing air, understanding how a heater works, in general, is useful. A heater is much like any other machine. It uses fuel to heat a series of coils called a heat exchanger. The heat exchanger has a fan, which is called a blower motor, and it blows the cold air inside of the house over the heat exchanger. The air then goes into the house’s air ducts to blow warm air into the house. While this seems simple, the numerous steps from powering the furnace to actual hot air blowing into the rooms leave multiple ways for the system to break down.

1. Check the Thermostat

The most common cause of a furnace not blowing air in the home is an incorrectly-set thermostat. Make sure to check with other people living in the house and ask if they’ve set the thermostat at the correct temperature. If the thermostat is not at the proper temperature, try adjusting it five degrees higher than the home’s current temperature. If the furnace’s fan still does not turn on, check the following:

  • Ensure the thermostat is in “heat” mode instead of “air conditioning” or “fan.” Programmable thermostats are sophisticated, and these settings may be challenging to locate at first.
  • Check the date and time of the programmable thermostat. Some thermostats have settings that only heat the home at specific times of the day. If the thermostat works incorrectly, this may account for the fan not blowing air when expected.
  • Replace the thermostat’s batteries. If all else fails, try replacing the batteries to see if the thermostat is improperly programmed because of a power outage. A thermostat might reset its settings when the battery is low, as well.

2. Check the Circuit Breakers

Another common cause of a furnace not blowing air is the circuit breaker. Make sure that the one connected to the heater is not turned off. Additionally, it’s not unlikely for the furnace’s fan to have a separate circuit breaker than the furnace itself, so make sure to check that one as well. After reviewing the home’s main circuit breaker, make sure to check around the heater, and the surrounding area for an on/off switch or another circuit breaker and make sure that it’s on.

3. Check the Air Filter

If the furnace’s air filter gets clogged with dust and debris, air can’t get through it to the home’s ducts. Filters need replacing every one to three months or so. Additionally, restricted airflow from a clogged air filter causes furnaces to overheat. Modern heaters have an automatic safety shutoff that turns the furnace off when it gets to a specific temperature. Unless the filter is brand new, replace it, and see if that fixes the issue.

4. Check the Furnace Fan

If none of the “easy” solutions above fix the problem, check out the furnace fan. To check the fan for proper functionality, first, turn the furnace off and then turn the thermostat to fan-only mode. If the fan turns on, the blower fan is not the problem because it’s running on its own just fine. If the fan does not turn on, go back and check the circuit breaker and see if it trips. If it tripped, call a professional HVAC technician to look at the unit as there is likely an issue with the unit’s wiring. If the circuit breaker didn’t trip, the thermostat or the blower motor is failing, and an HVAC technician needs to come to look at the unit.

5. Check the Limit Control Switch

The limit control switch is a thermometer attached to a switch in the furnace. The switch tells the blower motor to turn on and off. When the furnace is off, the limit control switch senses that there’s no heat generated by the heater and turns the blower off. When the furnace is on, the limit control switch senses the warm temperature and tells the fan blower to turn on to distribute that air throughout the home. Additionally, it turns the furnace off when it senses that the furnace is too hot. If the limit control switch isn’t functioning correctly, this may cause the fan blower not to blow air, even when the furnace is on. If homeowners believe the limit control switch to be the issue, they should call a licensed HVAC technician to come to the home.

Furnace Still Not Blowing Air?

If homeowners have gone through the above troubleshooting guide and still can’t figure out what’s causing the furnace not to blow air, they should call a licensed HVAC technician to check out the heater and keep the family comfortable.

How Can Desert Air Conditioning Help?

Desert Air Conditioning has served the Coachella Valley with comprehensive HVAC services since 1954. That’s right, for more than sixty years. Whether homeowners in the area need a more efficient home unit or business owners are looking for a new HVAC install, Desert Air Conditioning has the experience and the highly-trained staff to complete the job. Call today for a free quote and to get all HVAC-related questions answered by a licensed professional!