Table of Contents
- My Fan Kicks on But Compressor Not Working (Causes and Solutions)
- Final Thought
If your fan kicks on but compressor not working, you need to quickly find out what could be going on. AC fans and compressors are designed to work hand in hand. If anyone of them malfunctions, that can affect how other components work.
Some of the reasons for your compressor not working include a dead compressor capacitor, bad starter relay, or a compressor that is completely dead and needs replacement.
My Fan Kicks on But Compressor Not Working (Causes and Solutions)
Let’s briefly look at how your air conditioning system works to help us better understand what can cause your compressor to stop working when your fans are running quite alright.
If you are surprised when I said ‘fans and not fan, don’t worry. An air conditioner system typically has two fans. One fan that is usually found indoors to blow air throughout your home. The other fan is found in the outdoor ac unit well known as the condenser unit.
AC Outside Unit Fan Kicking on But Compressor Not Working
Let’s look at what can keep your compressor from working when your ac outside unit fan is turning on just fine.
Bad Compressor Capacitor
If your ac compressor won’t turn on but your fan is running, this could be a sign that the capacitor that powers your compressor is not working.
Newer outside condenser units come with dual capacitors, one part that powers the compressor and the other one that powers the fan motor. With time, any of these two parts can malfunction.
When part of a capacitor that powers the compressor dies, the other part that powers the fan motor could be working and giving it power. That’s why you might experience an ac compressor not working but fan is running.
When you have a capacitor that is nonfunctional, you may hear a humming sound coming from your AC outdoor unit. This is because your compressor could be trying to access power from a capacitor that is not working.
How do I fix a bad capacitor?
AC capacitors are the cheapest and among the easiest to ‘fix’ parts of an air conditioner system. To check the status of your AC capacitor, you need to do the following:
- Open the cover of your outdoor unit. But make sure you disconnect your ac unit from power supply by tripping the breakers and at the disconnect box.
- Open the condenser unit on the side where electrical wires attach.
- Once the cover is open, look at the capacitor. Do you see a capacitor that is bubbled on top? If do then the capacitor is definitely dead. If you can’t see any bulging on top of your capacitor, it could still be dead, but you need to test it to confirm its status.
- You need a mutimeter to test your capacitor. And remember before touching your capacitor, you need to discharge it of any voltage.
- You can discharge your capacitor by connecting any two terminals of your capacitor. If your capacitor is dead, you’ll need to replace it.
- Check all the details on your thermostat that you can use to buy a new one.
Bad starter Relay
A starter relay carries power from the capacitor to the compressor. If the starter relay is defective, the compressor will not be able to receive power to start. Just like with a capacitor, a relay starter can easily be replaced. It is a comparatively cheaper part of an ac unit, and it can readily be found on the market.
Is your air conditioner system over 10 years? If so, then your compressor has aged and could have just served its purpose in your home and now needs replacement. When your compressor is faulty, the best solution is to replace it with a new one.
Indoor Fan Kicks on But Compressor Not Turning On
So now, when your indoor fan is turning on, but your compressor is not running, this could be due to a bad capacitor, bad starter relay and a dead compressor as we have seen already.
Besides these issues, there are more issues that can prevent your compressor from running when your outdoor unit fan is able to spin without any problems. These include the following:
Wrong thermostat settings can also be the reason your compressor is not running. Make sure the ac mode or cool mode is on. Check if the temperature on your thermostat is lower than the room temperature reading. Otherwise, your compressor won’t turn on if there is no call for cooling.
And if you recently replaced your thermostat, check that the wires and terminals are in order specifically the Rc terminal (power for cooling). Make sure there is a jumper between the R and RC wire.
If you are not sure about what power goes on what terminal, you can find more information on wiring designation in the control board compartment.
If your air conditioner system is recovering from a power outage, your compressors can be going through a delay mode. A delay mode is a brief moment when your thermostat prevents your ac outside unit from starting. This is mainly in order to protect your compressor and other components from short cycling and potential damage. But usually, in delay mode the indoor fan should run.
Tripped AC Breakers
When power supply to your outdoor unit is cut or interrupted, your ac compressor will not turn on. Power cut can be the result of circuit breakers tripping. A locked compressor is what usually causes an AC system to trip breakers.
Check for tripped breakers and if you have any reset them accordingly.
Other issues that cut power to your outdoor unit include broken thermostat wires that connect to your outdoor unit, blown out fuses (in the disconnect) or on the control board panel in your furnace.
A defective ac contactor can be the reason your outside ac unit is not turning on. An ac contactor completes the circuit for the compressor and the fan to run. It’s a small device that is powered by a 24 v from your furnace. When there is call for cooling, the contactor will close, completing the circuit.
However, sometimes, your contactor might malfunction. When this happens, it can stick in the up position, so your unit will be cut off from power even when you turn on your thermostat. This is why you might have a fan inside working but your outdoor ac unit not turning on.
If you beleive you contactor is defective, you can easily replace it.
Whenever your fan kicks on but compressor not working, try going through these tips we have provided in this article to help you resolve the issue. We hope these troubleshooting tips have been helpful to you. Thanks, for reading
HVAC tech with over 30 years of experience. Retired and doing repair work on the side around Madison County, AL.