Why Is My Air Conditioner Fan Not Spinning?

Your condenser fan, not spinning can be caused by multiple issues. Listed below are some of the most common problems you can encounter. Skim through our list - we hope it helps!

*** Always best to shut the AC unit off if a problem exist.

Six reasons your air conditioning fan may not be running:
  1. Condenser fan motor failure
  2. Run capacitor is weak or has failed
  3. The dual run capacitor is defective
  4. Check the float switch 
  5. The contactor may be faulty
  6. Check to make sure your breaker has not tripped

Symptom # 1

 The condensing unit (outside unit) sounds like it is running, but the fan is not moving or moving slowly.

Possible reasons:

1. Condenser fan motor failure

Motor failure stops fan

A bad condenser motor can cause a compressor to fail. Without the fan operating, the refrigerant pressure skyrockets & puts a lot of strain on the compressor. Also without the heat dissipation, the whole condensing unit can get incredibly hot.
The leading cause of condenser fan motors failure, is a weak or dead capacitor. We recommend a yearly maintenance plan to help prevent this issue.

2. Dual run capacitor is weak or has failed

failed capacitor causing air conditioner fan to spin slow

In this scenario, you know power is present because you can hear the compressor running.

If the fan motor is running slow, it is likely the run capacitor either is weak or has failed altogether.

The run capacitor helps correct the "power factor" of the motor. It helps make the condenser fan motor more efficient.

Without the run capacitor in the circuit, the motor will still try to run and may spin slowly because it is now very inefficient - This is bad.

Shut the system off. Without the capacitor, in the circuit, the amp draw on the motor goes way up. This can damage the motor.

If the motor is still spinning albeit slowly, it is not moving enough air for your HVAC unit to function normally. Don't risk damaging your compressor.

**With the power off to your condensing unit, here is a simple test you can do. Take a stick or screwdriver and spin the fan blade.

If you can't turn it at all or if it's pretty stiff, it is likely your motor. If you can rotate the blade freely, there is a good chance it's your run capacitor.

Symptom # 2 

Condensing unit is not working at all

In this scenario you have the thermostat on set to cool, your air handler inside is running, but the outside unit is off.

3. The dual run capacitor is defective. A dual run capacitor is a capacitor that helps both the condenser fan and the compressor operate. Just as the name states, there are two different ratings of capacitance built into one capacitor. If this fails, everything is offline.

4. The contactor may be faulty.


Bad contactor stops air conditioning fan from spinning

The contactor is an electrical switch that breaks the high voltage to your condensing unit.

Obviously, if this part fails - no power to the air conditioning unit, nothing runs.

Float switch

Fan not spinning because of float switch

5. Check the float switch

The float switch isn't located at your condensing unit. It is actually at your air handler (inside unit).

The reason for this switch is to shut the unit down if the water stops draining to prevent damage.

Depending on how your system control voltage is wired this turns off the whole system or just the condensing unit.

If your air handler is horizontal, you should have two switches. Check both. One is the air handler near where the drain line exits. The other is in the secondary pan under the air handler.

If this pan has any water in it, remove the water, wet/dry vac or whatever means possible. Removing the water should reset the switch.

Make sure you clear the drain line otherwise it will just reoccur. If your air handler is vertical, most of the time the float switch is directly at the base of the unit.

Usually, it has a round white top with thin gauge wiring going to it. Be careful, but you can pull this up & look to see if any water is present. If so, clear it out.

6. Check to make sure your breaker has not tripped.

Breaker tripped - air conditioner fan not spinning

If you do find it tripped, it would be best to shut the system off at the thermostat. Reset the breaker - then turn on AC at the thermostat.

Most digital thermostats have a 5-minute delay so give it time. If the breaker trips again, call a professional.
** Most air conditioner split systems have two independent circuit breakers. One for condensing unit & one for air handler. Often the air handler is marked as "heat" or A/H.

Need a Professional A/C Technician?

Air Zero provides AC services in Largo Fl, St. Petersburg also Seminole, and Clearwater and all of Pinellas County. Give us a call at 727-392-6111.