Air Conditioner Outside Unit Not Running [Solved]

Is your air conditioner outside unit not running? This is a common problem with air conditioning systems and can be so frustrating to deal with it. Shortly, we’ll be looking at the possible reasons why your outside ac unit won’t turn on and what you can do to fix the problem. Some common issues that can prevent your ac outdoor unit from running include:

  1. Power supply issues
  2. Blown out fuses
  3. Failed capacitor
  4. Bad contactor
  5. Bad fan motor
air conditioner outside unit not running
A man inspecting ac condenser unit

Read also AC Condenser Unit Blowing Cold Air Outside

Why is My Air Conditioner Outside Unit Not Running?

There are few reasons your ac outdoor unit could not be running and many of these, are issues that you can easily fix yourself without calling professional HVAC guys. Let’s now dive right into these issues.

1)Power Supply Issues

When there is no power connection to your ac outside unit, it won’t turn on to run. Power failure can be the result of a tripped breaker or a power switch that is turned off.

Check that the breakers for the air conditioner are not tripped. Reset tripped breakers and flip back any power switches that are turned off.

Blown out fuses

Blown out fuses will cut power to your condenser unit, and it won’t turn on. After checking out with the circuit breakers and the power switch and things look good with them, you might have blown out fuses.

Head over into the control board compartment of your indoor unit and check if there are blown out fuses. Fuses can get blown due to a number of reasons including power surge

Some disconnects (found on the outside) can have fuses and any one of the fuses might have blown out after a thunderstorm or a power surge. You need to check them too.

Thermostat wiring

Wrong thermostat wiring can affect how your ac outdoor unit works. I won’t go into details on this one but if you recently replaced or installed your thermostat, you might have not connected one important wire for your ac.

On a typical thermostat wire panel, you will see the Rc and R terminal. You need to connect these two terminals to the wires. alternatively, you can use a jumper to interconnect them

2)Failed Capacitor

A dead capacitor is a common reason why your ac outside unit won’t turn on or run. Capacitors can fail due to a number of reasons. Sometimes a capacitor can just fail because of age. Other times, it’s the lightening that may kill the capacitor.

Whatever the case, when your capacitor dies, you will need to replace it with a working one. A capacitor that has failed will typically bubble on its top part so you can easily tell that its dead just by looking at it.

Other times a capacitor will just look like there is no problem with it even when it is not working. In this case, for you to test it, you will need a multimeter.

For you to access the capacitor, you’ll need to open the AC cover, specifically the section where the electrical components lie. You’ll also need a screwdriver to open the cover.

Check the capacitor for specifications before ordering a new one. If you are not comfortable with doing this, its always a good idea to call in professionals to come and give a hand.

3)Bad Contactor

A bad contactor is another electrical component of your air conditioner that can prevent it from turning on or running. A contactor is a part of your ac system that is responsible for starting and stopping the electric circuit.

When you turn on your air conditioner using your thermostat, let’s say for cooling. The contactor will conduct the electricity to all other parts of your ac outdoor unit so that it can start cooling your home. When you turn off your ac on your thermostat, like wise it cuts off electricity flow.

Sometimes this contactor can stick in one position, either in the upper position or the down position. Other times, bugs or other small objects can stick between it and this can prevent it from conducting electricity.   If the contactor sticks in the upper position, it will disconnect your system’s circuit meaning that your air conditioners unit will not run even if you turn it on using your thermostat.

Otherwise, when the contactor sticks in the down position, it will continue conducting electricity to any other component of your air conditioner. That’s why you might have an outdoor unit running even when you turn it off on your thermostat.

Read also: Air Conditioner Running But Not Cooling [Solved]

4)Broken Thermostat Wires

Sometimes mice or other small animals in your backyard can have access to your ac wiring that comes from your house to your outdoor unit. They might chew the cables, and this will cause problems operating your ac unit.

mice chewing wiring
mice chewing wiring

5)Bad Fan Motor

If your fan is not running when your ac unit is turned on try giving it a push with a long screwdriver or stick. If giving it a little push doesn’t make it spin on its own, the problem could be with the fan motor.

But if your fan can start spinning on its own after given it a little push, the problem could be with the start capacitor.

To fix a fan motor, open the condenser grill and remove the fan. Try to oil the fan motor. This will work for some time but should not be a permanent solution.

For a permanent solution you will need to replace the fan motor. Usually, when you replace your fan motor, you’ll need to replace the capacitor too.

Final Thought

Dealing with an air conditioner outside unit not running can be hard. But with the tips we put together in this guide, we hope that you will be able to spots the problem and fix it quickly before you have to call HVAC professionals to come. Thanks for reading.

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