The blower in your HVAC gets a lot of use since it blows out air for the furnace and air conditioner. This can cause the parts of the blower to wear down with age. A blower can break down for other reasons too, so when your HVAC isn't blowing air, the repair technician has to look at several possible issues. Here are four things that might be wrong.
1. Mechanical Failure
If the blower won't spin, or if it doesn't spin very well, the problem might be bad bearings in the motor or a bad belt. Not all blowers have belts, but if your HVAC is an older model, it might have one. When a belt or the bearings go bad, they are usually noisy, so noisy operation is a sign of impending failure of the blower.
The HVAC repair technician can put on a new belt or change the bearings. However, it might be necessary to put in a new motor if bad bearings caused the motor to overheat and burn out.
2. Electrical Problems
A variety of electrical problems can keep the blower from spinning. The HVAC repair technician may need to test the control board, wiring, capacitor, and motor to see where power is being lost. They might need to tighten wiring connections or put in a new capacitor. A capacitor is similar to a battery that gives the motor a power boost so it can start the blower when the HVAC kicks on. If it is bad, the motor may not be able to start up the blower, so the technician has to replace a bad capacitor.
3. Motor Failure
A blower motor might fail due to old age or because it overheated when the belt or bearings went bad. A motor can also fail if the blower is coated with dust and difficult to turn. When a motor burns out, the technician will replace it. The right type of motor is chosen and installed so the blower turns in the right direction for your model HVAC. The operation of the blower and motor are checked to make sure the blower is spinning properly and the repairs are successful.
4. Blower Damage
An HVAC blower looks like a squirrel-cage rotor rather than a typical fan with large blades. If the cage vibrates loose, it won't be able to spin properly and create enough air. A loose fan should be noisy, so if the blower has mechanical issues, you'll probably know it. Another problem with the blower itself that can lead to the need for repairs is when the blades in the cage get so clogged with dust, the fan has low airflow or the grime causes the motor to overheat.
The overheated motor might burn out, but your furnace might shut down instead. This happens when a safety switch turns the HVAC off. This problem can lead to short-cycling of the HVAC, and after a few episodes of short-cycling, your HVAC may shut down completely until repairs are done.