Why is my AC fan not spinning?
If you’ve noticed the fan has stopped spinning on your HVAC unit, you’re likely referring to a part called the condenser fan. Air conditioners and heat pumps both have condenser fans that are easily visible inside the top of the unit.
Condenser fans fail when their motors wear out, due to electric or wiring problems, because of insufficient airflow or dirt buildup, and when correlating parts of the unit stop working. If the fan isn’t spinning on your installed unit, a professional HVAC tech can properly diagnose the underlying problem quickly and effectively.
When should the AC condenser fan run?
The condenser fan plays a critical role in both the process of absorbing and releasing warm air and in keeping your essential AC components from overheating. Whether your home employs a combination air conditioner/furnace system or you have an installed heat pump to meet all of your heating and cooling needs, the fan will run as long as the system is on.
Austin homeowners with installed heat pumps will naturally notice the outside condenser fan running year-round. That’s because a heat pump’s outdoor condenser and indoor evaporator effectively switch roles in the winter in order to supply your home with heat.
Should the condenser fan always run?
No, your AC or heat pump works in cycles. Once the thermostat registers the set temperature has been achieved, the unit and the fan will stop running – unless your fan is set to ON instead of AUTO. That means if the fan on your HVAC unit is always on, it’s time to schedule a service call. Potential reasons the condenser fan won’t stop can include a faulty thermostat, an electrical issue, holes in the ductwork, or an improperly sized unit.
Symptoms of Common Condenser Fan Issues
When your AC’s condenser fan isn’t working properly, you’ll likely notice insufficient cooling or heating before you notice anything else. Additionally, signs of a problem with your condenser fan could include:
- Buzzing, humming, or clicking noises coming from the unit
- The fan sometimes rotates slowly or intermittently
- A distinct electrical or burning odor
- The outdoor unit feels hot
- A tripped breaker
Signs the Motor is to Blame for Your Condenser Fan Issue
The condenser fan is powered by a motor which, like any HVAC motor will become worn with age. When the condenser fan motor is broken or malfunctioning, you’ll notice that the fan on top of your outside unit isn’t spinning or is only spinning slowly or intermittently. The fan may also rattle while it’s running.
Signs the Capacitor is Causing Your AC’s Fan Problems
The capacitor helps provide the extra jolt needed to start your AC or heat pump, and to keep the motors running while your unit completes a heating or cooling cycle. The most common sign of a bad AC capacitor is that the motors won’t run or will run only sometimes. This means a bad capacitor can lead to a broken AC fan.
However, a bad capacitor also affects the compressor and other critical components of your HVAC system. In addition to a malfunctioning condenser fan, you may experience start delays after you’ve turned on the unit, intermittent function, random shut-offs, clicking or humming, a burning plastic smell, and unexpectedly high energy bills. A bad capacitor can also cause your circuit breaker to trip if the compressor doesn’t receive adequate starting power.
Signs that Electrical Problems Are Impacting Your Condenser Fan
Problems with your AC unit or heat pump’s circuit board or electrical wiring can cause the condenser fan to start and stop repeatedly, or quit working altogether. A malfunctioning contactor switch can also prevent the proper voltage from reaching your unit’s condenser fan.
If your unit is experiencing issues with wiring or circuitry, you may also notice inconsistent temperatures, electric or sulfuric odors, unexpected stops and starts, blown fuses, and tripped breakers, in addition to the fan not spinning on your AC.
Signs Your Condenser Fan Isn’t Working Due to Overheating
AC units need ample airflow in order to function at optimal capacity. When airflow is impeded, the unit can quickly overheat. The most common reasons for issues related to airflow are overgrown plants or yard debris around the outside unit, dirt buildup on the coils, and blocked vents. Improperly lubricated parts can also cause the motor to overheat and fail.
If you haven’t changed your filters recently or you’ve skipped regular maintenance this year, a malfunctioning condenser fan may very well be the direct result. Warning signs that your unit is overheating include electric burning smells, rumbling noises, the unit being hot (not warm) to the touch, and a repeatedly-tripped circuit breaker.
Signs You Have a Broken Condenser Fan Belt
If you have an older AC unit, it may utilize a belt to engage the condenser fan. The most common sign of a failing motor belt is a squealing noise and/or rubber smell while the AC is running or starting up. Because only older systems use belts, it may be time to consider replacing the entire unit with a new, more efficient model instead of investing additional money into repairs.
Condenser fan failure is a common issue with a wide range of potential causes. Because of this, a professional diagnosis for a broken condenser fan is recommended and usually required.
Regular HVAC maintenance can prevent fan failure and additional problems from arising by helping homeowners get ahead of issues related to faulty wiring, poor performance, problems with airflow, dirt buildup, refrigerant leaks, clogged lines, and more.