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Why Did My AC Stop Working? | 10+ Reasons for Your Air Conditioner Not Running

With the summer winds setting in, air conditioners in our houses have become of utmost importance. Dealing with a temperature of 90 F without an air conditioner sounds like blasphemy. But have you had the time to check if your air conditioner is in the right condition to be working? If not, you must do that before summer kicks in.

Here’s the deal with air conditioners, when you want them to work, it’s only then that they stop working. But why isn’t my Air Conditioner working suddenly? In case you find that your AC is not working, there are many factors to consider before calling up for professional help or replacing your old conditioner with a new one entirely.

Why isn’t My Air Conditioner Working?

The most common reasons that your AC or Air Conditioner stopped working randomly are as follows:

11 Reasons AC Not Working

1. Dirty Filter

Many people find that their air conditioning is not blowing out cool air as it should, and in the majority of cases, the problem lies within the unclean filter. If you do not change and clean the filters regularly, they will get clogged with dust and gunk and prevent the proper airflow. If the same continues, the coil and the system can freeze up, which is not healthy for the machine.

The coil may freeze up due to other reasons, like refrigerant leaks, obstructed return or supply vents, improper refrigerant charge, and the closing up of the supply vents. Nevertheless, a dirty air filter is a major and most common cause. However, you can keep AC from freezing up by taking some preventive measures.

2. Dead Capacitors

An air conditioner normally runs on two capacitors, one installed in the indoor unit and one in the outdoor unit. Capacitors are giant batteries that hold power and allow the air conditioner to turn on and stay on after that. Unfortunately, the capacitors have a short shelf life and need to be replaced.

3. Broken Fuse

A blown transformer or a fuse may be the reason behind the A/C not working. In reality, there are two fuses; one that is connected to the thermostat, and one is an internal fuse. Unless you have specific knowledge and expertise, it is advisable to call a heating and air company to fix the issue.

4. Dead Thermostat Batteries

Sometimes, there is nothing wrong with the air conditioner but with the thermostat. The batteries in the thermostat dry out, and as a result, it displays nothing. The solution is extremely simple, replace the old batteries with new ones.

5. Damaged Components

In any household, wherever your indoor and outdoor units of the air conditioner have been placed, it is natural for someone to damage the parts of it by mistake. Maybe you busted the refrigerant line or pulled a wire, or worse, somebody knocked over the outdoor unit while playing. Everything is possible, and in such cases, calling the company to send a professional to fix the air conditioner is your best option.

6. Dirty Coils

If the air blowing out of your air conditioner is not the one set on your thermostat, there are high chances that the coils, both indoor and outdoor, are dirty. The coils in the outdoor and indoor unit will stop doing their job if they are dirty. Therefore, make it a point to survive your air conditioner regularly. In cases where the coils are way too dirty, the whole system won’t perform, and you will need to have the coils changed.

7. Blown Transformer

Having a blown transformer is similar to a blown fuse. Even though they are two different problems yet the result is the same. Wiring issues or a short circuit in the wires may cause the problem. Getting a professional to do the job would be the best solution.

8. Tripped Circuit

Breaker boxes often tend to trip if the circuit is overloaded. So if your AC doesn’t work, check the breaker box to see if any breakers have tripped. If there’s an influx of electricity, electricity often trips. Try to find the equipment responsible and turn it off completely. Fixing the breaker box is an intermediate job, and you would want to consult an electrician in some cases.

9. Indoor Disconnect Switch is Turned Off

In most cases, as it happens, the indoor disconnect switch gets turned off. It is usually because of where it is located as people may bump into it and accidentally turn it off. So make sure that the disconnect switch is always set to “on” before going for heavy fixtures.

10. Outdoor Disconnect Switch is Turned Off

Many building codes direct that the switches to the air conditioner should be installed to both the indoor and outdoor units. So don’t be surprised if you find your outdoor disconnect switch turned off. It might have been turned off due to several reasons, but it’s easy to locate and reset it.

11. Fan Problems

When the air conditioner has not been put to use for the entirety of winter, the fans of the air conditioning system not working. This is because they have a hard time rotating because of all the dirt buildup. There are ways by which you can start the fans manually, but if the problem persists, it is for the best that you call for professional assistance.

Time of your Air Conditioner has Come – When to Replace?

If the air conditioner has stopped running and your diagnosis finds no fault, maybe it’s time that your air conditioner has reached the end of its lifespan. However, if you aren’t able to exactly tell whether that’s the case or not, then here are a few signs you should look for:

  • You notice a considerable drop in the airflow of your air conditioner. Dirty filters can cause reduced airflow, but if cleaning the filters does not help, your AC has aged and has to be replaced.
  • Your AC requires maintenance services from time to time, which might indicate whether your AC is experiencing difficulties relating to its lifetime.
  • Your bills are escalating at an unusually rapid rate. When an air conditioner reaches the end of its useful life, it becomes sluggish and overworks to maintain the intended temperature, increasing expenses. You may get an energy audit to check if it’s truly your air conditioner that’s causing your rates to rise.
  • Your air conditioner’s internal unit is leaking heavily. It might be due to a refrigerant leak, but it’s time to replace the unit if the problem isn’t remedied.
  • If your air conditioner produces strange loud noises like grinding, screaming, or rattling, it’s time to replace it since it indicates a major problem.
  • Your air conditioner stinks. It might be mold developing within your unit or filthy filters, but if the scent persists, consider replacing it.


Using an air conditioner at least a decade old might be the root cause for problems. If you don’t know why isn’t AC working, you would want to replace the whole unit. But if you could spot the issues with your air conditioner on your own and fix them, then kudos to you! If your AC still won’t work, we recommend you seek professional help for it.