Common Reasons Your AC Isn’t Working

Nothing is worse than finding out your air conditioning has stopped cooling in the peak summer heat. From dirty filters and thermostat settings to low refrigerant and clogged drains, these smaller problems can become larger, more costly repairs if you don’t take care of them right away.

Fortunately, most of these problems can be identified—and sometimes fixed—without calling a technician. In this guide, we will break down the most common failure reasons for your air conditioning unit, the signs of your air conditioning unit’s failure, and how you can address your air conditioning unit problems.

10 Common Issues with Air Conditioners – How to Fix?

Air conditioning units work diligently to provide home comfort, and like all machines, they are also subject to issues. The most common AC issues, why they happen, and what you can do are listed below.

Following are the most common issues with air conditioner:

• AC not working
• AC not cooling
• AC not blowing cold air
• AC not turning on
• Air conditioner stopped working
• AC fan not spinning
• AC running but not cooling
• AC fan not working
• AC making noise
• AC leaking

1. AC Not Turning On

If your air conditioning system isn’t turning on, it may be an easy fix, such as resetting your circuit breaker, blowing a fuse, or a malfunctioning thermostat. In some cases, poor wiring or internal electrical faults could possibly keep it from turning on.

How to Fix?

• Examine your circuit breaker and reset if necessary.
• Change batteries in the thermostat and also check that it’s properly set to cool mode.
• Be sure that the main power switch located next to the outside unit is in the “On” position.
• If the air conditioner won’t start, chances are it is most likely an internal wiring issue, and should be referred to and examined by a licensed HVAC technician.

2. AC Not Cooling

There is almost nothing more irritating than turning on the ac unit and getting warm air rather than cold. When your ac is blowing warm air, it’s one of the most common ac problems. There are many culprits for warm air blowing from the unit, including:

• Dirty air filters, which can restrict air flow
• Low refrigerant levels from leaks
• Clogged or dirty coils outside in the condenser unit
• Faulty thermostat settings or malfunction
• Frozen evaporator coil from low refrigerant levels or not enough airflow

How to Fix?

• If the air filter is dirty, replace it or clean it—this must be done every 1–2 months during high-use season.
• Check your thermostat settings. Make sure it is set to cool mode, and is a lower temperature than the room temperature.
• Check the outside unit for debris, leaves, or other items that can block airflow—if dirty, clean gently with a hose.
• If you suspect a refrigerant leak, or a frozen coil, turn the unit off and call a licensed HVAC professional.

3. AC Blowing Warm Air

In the event of blowing warm air, it typically signifies low refrigerant level, a dirty air filter, and/or a clogged condenser coil. Low refrigerant levels may be due to a leak that is impacting cooling performance.

How to Fix?

• Replace/clean the air filter, a dirty filter will restrict flow.
• Check the outdoor condenser unit and clean debris around it.
• If the refrigerant is low, only a professional can recharge it and repair leaks.

4. Weak or No Airflow

Restricted airflow is frequently caused by dirty filters, blocked ducts, or a failing blower motor. This has the effect of limiting the effective cooling of the unit, and at the same time, strains the whole system.

How to Fix?

• Change out filters every 1–2 months during peak use.
• Make sure all vents and registers are open and not blocked.
• If you are still having airflow problems, your blower motor or fan may need to be repaired by a professional.

5. AC Leaking Water Indoors

If you’ve got puddles of water accumulating near your indoor unit, you could potentially have a clogged condensate drain line that is either filled with dirt or algae — or, you may be experiencing water due to excess buildup from a frozen evaporator coil.

How to Fix?

• Use a wet/dry vacuum to clear the drain line, or flush with some vinegar to restore the drain line before plugging it back in.
• Next, confirm whether there is any excess ice buildup on the coil — unplug the unit and let it thaw if there is.
• If puddles continue to build, contact an HVAC tech to inspect for drainage issues or to further inspect the coil for freezing issues.

6. AC Making Strange Noises

Uncommon sounds are generally indicative of a warning. Grinding could mean an issue with the motor, hissing may mean you have refrigerant leaking, banging or rattling usually means you have loose parts.

How to Fix?

• Tighten loose screws or panels.
• Replace any worn fan blades if they are wobbling.
• If you hear anything hissing or grinding, shut the unit off completely and consider calling a professional.

7. Bad Odors from AC

A musty odor means mold is growing in the ductwork or drain line. A burning odor may be a signal of electrical problems or overheated components.

How to Fix?

• Clean or replace the air filters.
• Flush the drain line to remove the mold and mildew.
• If you have a burning smell, turn the unit off right away and contact a technician.

8. AC Constantly Running Without Cooling

If your air conditioner unit is continuously running and just doesn’t seem to cool correctly, the cause may not be an overheated system, but could be something like a dirty filter or low refrigerant levels, or potential thermostat issues. Another issue could be that you are running an undersized AC unit.

How to Fix?

• Change the filter and check the settings on your thermostat.
• Check the coils for ice accumulation.
• If the running continues, a technician should check the refrigerant levels and inspect your unit’s output in relation to capacity.

9. AC Fan Not Spinning

The fan located in your outdoor condenser unit is essential to the cooling process, as it rids the refrigerant of heat. Without a spinning fan, your AC will not work. Common reasons your fan stopped spinning are:

• A bad capacitor (the little part that starts the motor)
• A bad fan motor
• Debris that is interfering with the fan blades
• A bad belt or wiring that is loose

How to Fix?

• Always turn power off to the unit before working on it.
• Look for visible debris or obstructions blocking fan blades and remove gently.
• You can also try to gently push the blades with a stick (power OFF) and if they move freely, it’s likely electrical rather than mechanical.
• If the fan does not start after removing debris, you may need to replace the capacitor or motor, in which case you should contact a licensed HVAC technician.
• Do not attempt to repair electrical parts if you have not been trained to do so—it can be dangerous!

10. High Energy Bills from AC Use

If energy bills take an unexpected spike bigger than usual, it is a sign that the system is overworking itself, maybe due to clogged filters, dirty coils, or refrigerant issues.

How to Fix?

• Change filters often.
• Schedule annual maintenance, where you can have the technician clean coils and check refrigerant levels.
• If your unit is over 10–15 years old, and if you want to increase the efficiency of your making it a no-brainer, you might want to ask the technician if it’s time to upgrade to an energy-efficient model.

Still Facing Issues? Call Appliance Medic

If you have tried all the usual fixes, and you’re still having trouble with your air conditioner, it’s time to call in the pros. At Appliance Medic, we are dedicated to quick, reliable, and affordable air conditioning repair services you can trust.

Our trained technicians service all makes and models of air conditioners, and we offer same-day or next-day service with a 90-day parts and labor warranty so you can rest easy knowing your comfort is our business.

Don’t let air conditioning issues ruin your day! Contact Appliance Medic today and get your broken air conditioning system operating at peak performance.