5 Signs Your Furnace Needs a New Motor Blower

Nov 22, 2020Blog, Heating

No one wants to have their HVAC system fail when the weather is cold in winter, or blazing hot in summer. If your central heating and cooling system isn’t working correctly, you must identify the issue, and get it fixed.

There are many things that can cause your air conditioning and furnace system to operate incorrectly. Sometimes it is a broken component that needs to be replaced. In this article, we look at some signs that your furnace blower motor is malfunctioning, and when you need to have it replaced.

How Furnace Blower Motors Work

The blower motor in your HVAC system blows the heated or cooled air through the vents in your home. The air that is heated by your furnace or cooled by your AC unit moves through your home until each room reaches its desired temperature.

There are two main types of drives in furnace blower motors:

  • Direct drive motors connect directly to the furnace blower wheel. These are the most common, and most modern gas furnaces use these types of motors.
  • Belt drive motors are less common for residential furnaces, as usually only very old furnaces use belt drive. In a drive belt motor, the motor pulley is connected to a fan pulley mounted on a shaft to turn the blower wheel. You will sometimes see belt drive motors in commercial heating and cooling.

With residential furnace blower motors, there are also two types of speeds:

  • Single speed blower motors blow air at one speed: full blast until the target temperature is achieved. When the temperature is hit, it shuts off. When the room temperature falls out of range, then the single speed blower turns on again.
  • Variable speed blower motors operate at different speeds, as the name implies. One thing that might be counterintuitive is a variable speed blower is more energy efficient. This is because it keeps the temperature of your home evenly distributed. When the target temperature falls out of range, the variable speed blower operates at a lower speed. When the temperature gap is large, the blower operates at a higher speed.

What Causes Blower Motor Failure?

Like other components in your HVAC system, the blower motor can wear down over time. Some of the reasons a blower motor might fail are overheating, and excessive moisture. When dust, dirt, and debris build up, it can cause the windings and bearings to burn up more quickly. Furnaces are usually installed in an out-of-the-way location, like the attic, basement, garage, or utility room. Blower motors that are clogged with debris, or that become saturated with moisture can fail due to overworking or electrical shorts.

Something to consider when replacing the blower motor in your HVAC system is how often you are paying for repairs. Most residential furnaces should last between fifteen and twenty years. Regular HVAC maintenance can extend the life of your furnace even longer. However, if you are paying to replace the blower motor every few years, and the life of your furnace is getting older, it may make more financial sense to get a replacement furnace instead of paying for increasingly frequent repairs.

What Are Signs Your Blower Motor Needs to Be Replaced?

These are some sure-fire signs that your furnace motor blower needs to be repaired or replaced?

1. Poor or Airflow from Air Vents

This will be the first and most obvious sign your blower motor has a problem. It may or may not indicate that you need a replacement motor. If there is no air or very weak airflow coming from the air vents, the motor may be clogged, or it may be malfunctioning. It is possible that the motor is clogged with dirt and dust, or has a bad capacitor, or there may be leaky air ducts. If the motor has been overheating, has been saturated with moisture, or is nearing the end of its service life, it might need to be replaced. A licensed HVAC technician can tell you exactly what the issue is if you’re experiencing weak airflow.

2. No Airflow At All From Vents

If there is no air at all coming from your air vents when you turn on the heat, the blower motor may be completely broken. Getting a replacement motor blower would be the only choice at that point. There could be other reason why there is no airflow altogether, such as a bad relay, a faulty thermostat, or a fan control issue.

3. Skyrocketing Energy Bills

The blower motor is the component in a central HVAC system that consumes the most energy. If you already have a variable speed blower motor in your furnace, and the motor is not clogged with debris, the motor may be wearing down and approaching end of life. Dirty blowers need to work harder to push conditioned air through your air ducts, but this can also be a sign of a deteriorating blower motor. It is also possible that your air ducts have a major leak.

4. Strange Noises When You Turn on the Heat

If you hear strange noises when you run your furnace, such as squealing, screeching, rattling, or clanking, call a heating contractor at your first convenience. Some issues may be repaired easily, but others may require a blower motor replacement.

Screeching or squealing noises can be indicative of bearing problems in direct drive furnaces, or belt issues in older belt drive furnaces. Now, if your heating system is making rattling or knocking sounds, that usually means a broken or damaged part. Banging sounds are more serious, and sometimes means that the blower motor must be replaced. A qualified HVAC technician needs to make a thorough inspection to confirm what the problem might be.

5. Overheating Blower / Weird Smells

If you have an overheating blower motor, there will be clear signs. One would be a burning smell coming from your air vents every time you run the heat. Another sign is if the system shuts down, or if the blower stops while you are running the heat. This means the blower motor is overheating. If your system is shutting down to prevent electrical damage, or if the blower is shutting down, call a licensed HVAC contractor as soon as possible.

Replacing Your Furnace Blower Motor

Your local licensed HVAC contractor can help you find and install the correct blower motor for your HVAC system. The heating contractor must get some information about your furnace and take a few things into account, including the type of drive, the diameter of the motor, rotation direction, horsepower, voltage, speeds, and size of the capacitor. Based on these details, the HVAC company can make the right recommendation, give you an estimate, and schedule an installation.

Finding a HVAC Contractor for Heating Repair

Ventwerx HVAC can help homeowners with a replacement blower motor for your furnace, or any other residential heating repair. We serve the San Jose area, as well as Morgan Hill and Gilroy. We are licensed and bonded, and have served the South Bay and Central Coast since 2007.

If you need furnace repair or furnace replacement, fill out a service request, or call (408) 422-2987 in San Jose or (408) 710-9595 in Morgan Hill.