Once your furnace has heated the air within it, the blower motor is responsible for turning a fan to circulate that warm air out of the furnace and into your home. It’s up to this device to ensure that your home reaches the temperature set on your thermostat.
Blower motors work in one of two ways: as single-speed or variable speed blower motors.
Single-speed motors turn on when the thermostat indicates the interior temperature has dropped and turn off when that temperature has been reached. Because they operate at only one speed, these motors are using the maximum amount of energy when turned on.
A variable speed blower motor, however, moves at different speeds to better control the flow of air throughout your home. Furnace manufacturers say that these variable speed motors provide better energy efficiency because they are able to operate at lower speeds when appropriate, thereby consuming less energy than single-speed motors. In addition, by operating at a low speed for long intervals, these motors are more frequently circulating the air in your home than their single-speed counterparts and preventing cold spots. Operating at this low speed also helps to minimize the unit’s noise.
Types of Motors
You also might see furnace manufacturers advertising permanent split-capacitor (PSC) motors versus electronically commutated motors (ECM). ECMs are used primarily in variable speed furnaces as they are controlled by a microprocessor within the unit that signals as to how much heat is needed. ECM motors, which are comparatively new to the scene having been introduced in the 1980s, are more efficient than PSC motors, even when used in single-speed applications, according to HVAC technicians.
HVAC technicians say that one of the first indicators that your blower motor is in need of maintenance is that your furnace is running non-stop while your house remains cool. This happens because the air is being warmed by the furnace but not dispersed into your home. To prevent such problems, regular maintenance is important. If your furnace has a PSC motor, a licensed contractor should regularly lubricate the blower motor with oil ensures that the fan is able to turn easily (ECM motors use ball bearings and therefore require little or no oiling). Consult your furnace owner’s manual for directions on properly oiling your blower motor and other maintenance suggestions.
Question and Answer
Question: Why might the blower motor go bad in a Trane XL90 Furnace?
On 2014-10-11 Patrick wrote:
There are a number of reasons why a blower motor could go bad. If the ductwork is not right it can put a lot of strain on the blower motor. Remember that blower motor is moving a lot of weight, thousands of pounds of air per hour and if you don’t have the right amount of return and supply air for the unit the motor can be put under a lot of added stress. If that’s the case it will continue to take out blower motors. If the blower wheel is out of balance that can take out blower motors, I’ve seen in as quick as 1 year. When you replace a blower motor, it’s good practice to replace the wheel as well. It does not take much to put one out of balance, and sometimes it is a wrestling match getting the wheel of a old motor.
Question: The furnace blower does not seem to be as powerful as before.
On 2016-06-17 Gary wrote:
There are a few possible causes for this problem. It could be a dirty filter. It could also be closed or partially closed vents or dampers, or an obstruction in the ductwork. There may also be a problem with the blower motor.
Check the filter first. If the problem is not with the filter, it may be a good idea to contact a heating professional to troubleshoot your furnace.
Question: When we started to use our Carrier Comfort 80 a few days ago the blower came on but it never ignited the furnace so we have no heat. I cleaned the dust from the air intake upstairs — still nothing. Help if you can — furnace is in the basement.
On 2015-10-15 Chris wrote:
Couple of ideas for you. The manual for your furnace is here and Carrier has provided instructions for startup.
(They also offer the following warning: “If a suspected malfunction occurs with your gas control system, such as the burners do not light when they should, refer to the shutdown procedures on inside of main furnace door, or in the “Shutting Down Your Furnace” section and call your dealer as soon as possible.”)
Question: Blower fan wont come on Carrier Weathermaker
On 2012-11-25 JB wrote:
First, consult your owner’s manual for information on what to do if the blower shuts down or is not working properly.
Are you getting any sort of error code? The LED code can be seen by removing the access door and viewing the LED(s) through the view port in the blower access panel.
Without more info it could mean there is something wrong with the control board, possibly the thermostat (not sending the call for more heat), the blower motor, or any combination of these issues.
Question: Is the Goodman gas furnace EEM motor worth it?
On 2013-02-22 JB wrote:
EEM stands for Energy Efficient Motor so it is designed to be more efficient at heating and cost less. The way to assess if it is worth the cost is to estimate the reduction in energy usage versus the additional cost of an EEM motor. The result would depend on what the gas rates are near you and what you are being charged for the motor. Getting this right will also depend on the size furnace you need.
Question: Rheem furnace makes a grinding sound when the blower starts.
On 2016-02-05 Gary wrote:
This sounds like a problem with the blower motor, possibly a problem with the bearings. You should contact a technician and try not to use the unit until it is repaired to avoid causing more damage.
Question: Blower won’t stop on my Trane XB80 furnace.
On 2016-03-03 Gary wrote:
This may be a problem with a relay or a faulty circuit board. Some homeowners can change a circuit board but it involves disconnecting and connecting wiring as well as removing it from a mount, so unless you have experience with this it’s a good idea to hire a heating contractor for this kind of job.
Question: Can I run the blower motor continuously on the Trane XR80?
On 2014-07-29 Danielle wrote:
According to the manual you can run the blower motor continuously. Here is the excerpt from the manual: AIR CIRCULATION – To ensure increased comfort, the blower on this unit may be operated continuously for both heating and cooling. This will result in constantly filtered air and aid in maintaining more even temperatures by avoiding temperature stratification throughout the conditioned area. To accomplish constant air circulation, set your comfort control fan selector to “ON.” Continuous fan mode during COOLING operation may not be appropriate in humid climates. If the indoor air exceeds 60% relative humidity or simply feels uncomfortably humid, it is recommended that the fan only be used in the “AUTO” mode.