Why Is Air Conditioner Running But Not Lowering Temperature?

There are a lot of possible reasons why an AC suddenly stopped cooling your working space. Common issues include clogged evaporator coils or frozen condensate drains.

Most of these issues are easily avoidable with proper maintenance. An AC unit doesn’t need daily maintenance, but regularly checking on its parts is recommended.

Isn’t it frustrating when the AC suddenly stops working in the middle of a hot day? This unlucky scenario can ruin anyone’s day and can cause a bit of an unproductive streak.

Some of the most common problems can cause an AC unit to fail in cooling down your home. And these causes are featured in this blog. 

How Long Should The Air Conditioner Run To Cool A House?

There are a lot of factors that can affect the best AC runtime. Outside temperature is probably the biggest one, especially if we add high humidity to the equation. Your AC would need to run extra during the hot days of summer. Your room or your house will get harder to cool down because the outside temperature is high. 

However, during the milder temperatures (e.g., spring and fall,) the required temperature is lower. Hence, you don’t need to run your AC for an extended period to cool down your home. During these seasons, the expected AC run time is about 15-30 minutes at a time.

Take note: the Department of Energy recommends setting the temperature at 78° Fahrenheit. This setting gives the best comfort without consuming a considerable amount of energy. 

It would help if you also considered other factors, such as the size of your home or the designated area. The installed AC might not be able to cool it down if it’s too small to cover the whole area.

Additionally, expect older ACs to run longer than their newer counterpart. Older units are not that efficient, especially if not maintained properly. 

Does Turning The Thermostat Down Make It Colder?

It depends on the season and what you’re trying to achieve. During the summer, you turn down the thermostat to lower the temperature. Meanwhile, the higher temperature setting will make your area warmer during the winter. Your AC system tries to match the programmed temperature in the thermostat. 

AC units will follow your thermostat setting, so it’s essential to know how to use this device efficiently. By properly setting your thermostat, you can save energy with the least effort and no sacrifice to the cooling effect that the AC can offer. 

Take note: there is no “one setting fits all” thermostat option. However, turning your thermostat dial to a lower setting will not cool down your home faster. It will only add more cost to your electricity bill. 

7 Reasons Why Air Conditioner is Running but not Lowering Temperature

1. Dirty Air Filter

The air coming from the vent is filtered correctly to keep it clean and allergen-free, and dust-free when recirculated in the room. Unfortunately, these specks of dust and other light debris can clog up the air filter when enough particles have accumulated. This dirt layer results in clogging and inefficient airflow in the Ac system. 


If the air filter can still be salvaged, proper cleaning can do the job of removing the clog. Turn off the AC, remove the filter from the system, and rinse it until no other particles are left. However, if the filter is too dirty to function, it’s better to get a new one and replace the old ones.

Replacing the air filter is easily doable and doesn’t usually require help from a pro. 

2. Grimy Evaporator Or Condenser Coils

Both of the AC coils can cause a bit of a problem when dirty. In the evaporator coil, the refrigerant will not be able to cool down incoming air due to the clog from the dirt layers. Meanwhile, a clogged condenser coil means that the warm air is not properly disposed of outside


It’s essential to clean your evaporator coil and condenser coil as soon as possible. Further dirt accumulation can cause the coils to rust and break. When this happens, the refrigerant inside the coil might leak. Unfortunately, you have to replace the coils once they are corroded. 

3. The Blower Motor Is Faulty

The blower motor is the component that makes your AC fan run. This component is the one responsible for circulating the outgoing air back to your rooms at home. If this motor fries up, no cooled air will be circulated in the covered area. Even if there is no problem in your AC unit, no cool air will come from your vent


To avoid premature replacement, the best thing you can do is to keep a proper blower motor maintenance. If the blower motor completely fries up, there is no other solution but to replace it. You might need to contact an HVAC pro to get the replacement done. 

4. Wrong AC Type

Sometimes, there are no defects or malfunction in your system. It’s just that it’s too small to cover the designated area. If your AC is too small, or if you’re using the wrong AC type, it will fail to cool down your house completely. 


You can do two options: replace your AC with the right one, or pick a single, smaller space for AC usage. By doing this, you can make the best move for your current budget. For those who have a limited budget, you might want to focus your AC’s power into a single, convenient space. 

5. Thermostat Problems

The thermostat is usually one of the most overlooked reasons for AC malfunction. After all, the other AC components tend to break more than the thermostat itself.

But this component can also cause your AC to cool down inefficiently. It can either make your AC stop working completely or cause it to turn on and off frequently, preventing a successful area cooldown. 


Chances are, you would likely check your AC first before checking your thermostat. If there is no problem with the AC unit itself, try to replace your current thermostat with a new one and see if it fixes the problem. 

6. Other Broken Parts

Different things might suddenly break in an AC unit. One day, the whole system is properly working. The next day, you might find it non-functional due to a leak or a broken part. It can be the compressor or the capacitor; it can also be the control board or the thermistor. 


Unfortunately, if you cannot determine what causes your system to stop working, it would be better to call an HVAC repair professional. The parts listed above are somehow manageable even if the user has no HVAC experience. If you cannot identify the problem, turn off your AC and ask for professional help. 

7. Leaking Refrigerant

The refrigerant, or the one that cools down the air, will not “leak” in normal circumstances. This refrigerant will move inside the coils undisrupted until the whole AC system either breaks or other parts of the system dies out. However, a refrigerant leak can happen when the evaporator coil or the condenser coil gets heavily corroded and breaks. 


The only solution for this problem is either coil repair or replacement. Both are not doable by some with no HVAC experience. Just like the final option above, it might be better to hop in a call with the nearest HVAC repair pro in your area. 

Maintenance Tips to Make Sure Your AC Is Working Properly

Coil Cleanup

You can perform coil cleanup using a coil cleaning spray. If this item is not available, a simple dish detergent brushing and water rinsing should do the job. Make sure to finish with half-half water and a white vinegar mixture to disinfect your coils and kill the algae or mold on them. 

Air Filter Maintenance

The recommended air filter replacement is about every 90 days. 

At this period, you can either clean it or replace it if it’s too worn out. Most AC professionals would go on and recommend 45 days to avoid complications. But since it would depend on how often you would use your AC, you should be able to successfully decide on whether you’re replacing it early or on a later date. 

Condensate Drains Checkup

The condensate drain can also get clogged up due to dirt and algae build-up. Make sure to check it regularly for clogs and remove any build-up if there’s any. And make sure to disinfect it as often as possible if you’re living in an area with high humidity.


There are a lot of factors that can cause your AC to stop working suddenly. Either way, you might need to clean the parts, repair them, replace them, or leave them to your trusted HVAC operator. 

Take note that these problems might need a bit of funding, especially for replacing a non-functional component. AC maintenance is the key to prolong your unit’s useful life, as well as preventing frequent malfunctions from happening.