HVAC Repair Tips


The nightmare of every homeowner is their HVAC system not cooling when it’s scorching outside. You would want to fix your air conditioner immediately. Therefore, we have listed down the common reasons for an HVAC system not cooling. Some of these problems require an expert from AC repair services.

Clogged Registers

Your air conditioner requires proper airflow to cool your house. Registers help in distributing air inside your house. The supply vents blow cool air into your house while return registers are responsible for taking air into the air conditioner for cooling. This cycle of airflow ensures a cool house.

However, if the registers are blocked or clogged, the airflow will be impacted and your home won’t be as cool. However, this is not the main problem. When the airflow is restricted, the air conditioner works harder to reach the temperature you have set. During this, it overheats and the breaker is tripped. When this happens, the compressor stops functioning and the AC blows warm air. Additionally, your AC overworks and the components wear off quickly leading to repairs.

Therefore, you should check out the registers. They can accumulate dust and become clogged. So, remove them by unscrewing the screws and clean them.

Moreover, check if any register is closed. Even if you’re not using all the rooms, the registers of the unused rooms should not be closed because it can put stress on the HVAC system. Lastly, look for anything blocking the registers like curtains or a piece of furniture.

Dirty Air Filters

Air filters are usually located in the return air duct or right next to the air handler of your HVAC system. They keep the air clean so allergens and dust particles don’t circulate indoors with the cooled air.

As they keep cleaning the air, air filters become clogged with the particles and allergens they filter. Due to this, the airflow is restricted and the same problems occur that we explained in the above section. The AC overheats trips the breakers, and then blows warm air.

So, what you need to do is clean your air filters every 2-3 months depending on your usage and the dust and pollution level in your area. Washable air filters are cleaned while disposable air filters are replaced when they become dirty. Washable air filters can last for 5-10 years.

Low Refrigerant

The refrigerant is the gas that circulates inside the condenser and evaporator coils of your air conditioner. It changes its state to liquid and then back to gas for cooling the air that is blown into the house through the ducts.

If the levels of the refrigerant become low, it will directly hit the cooling efficiency of the HVAC system. The AC won’t cool the air effectively and your house won’t feel cool enough. The AC will take longer to cool the house and you may also notice that the air coming out of the vents is not as cool as it was before.

Low refrigerant levels also lead to the freezing of evaporator coils and the AC stops cooling. It also leads to water pooling near the AC unit. Moreover, the AC overworks and impacts your energy bills as well.

Low refrigerant levels in an air conditioner occur due to a leak. So, all will be in vain if you refill the refrigerant and don’t fix the leaks first. You should check the components of the AC and be attentive for a hissing sound. But the better method is hiring an expert to inspect your HVAC system for leaks.

Faulty Thermostat

The thermostat is the device you use to control the temperature of your house. If it becomes faulty, the AC will behave weirdly. It might keep running constantly, begins short cycling, or start blowing warm air.

But you should check the thermostat settings first. Make sure they are correct. Plus, a wrongly calibrated thermostat can also show similar problems, so call in an AC expert who can check your thermostat to determine if it’s miscalibrated or faulty.

If it’s miscalibrated, the technician will calibrate it only, but if it’s malfunctioning, then the thermostat will be replaced.

Problematic Coils

HVAC systems have condenser coils that are installed in the outside unit and evaporator coils which you can find in the air handler unit. These coils remove heat from the air and make it cool.

The condenser coils receive a lot of dust and debris which can clog the coils. Due to this, the compressor will work harder and it will lead to ice formation on the coils. Moreover, evaporator coils are prone to freezing if the compressor overworks or if the refrigerant is low.

So, many problems can occur with condenser and evaporator coils. If you can, you should clean the condenser unit of your AC first to check if your air conditioner begins cooling. If it doesn’t, you should let an AC technician inspect the coils and other components.

Leaking Air Ducts

When the air handler blows cool air, the conditioned air flows through the ducts to reach different parts of your house. If there is a leak in the ducts, cool air will escape through the leak and warm air might also enter. So, you will notice that your AC is not cooling enough, or if the leak(s) is severe, you may feel only warm air coming out of the ducts.

A leak in air ducts can occur due to damaged ducts or poor installation. If you suspect an air duct leakage, you will only have one option to get the entire ductwork inspected because the leak(s) can be anywhere. Moreover, you should have your ducts inspected annually to avoid problems.

Clogged Drain Pipe

Your AC absorbs humidity from the indoors, turn it into liquid, and flows it through the drain pipe out of the house. Due to debris, leaves, and the growth of microorganisms, the drain line gets clogged and impacts the cooling efficiency of your AC. It also results in water leakage. So, clean the drain line of your AC.

The Size Of The AC

The size of your AC impacts its cooling efficiency as well. It may be easier to understand that a smaller AC won’t cool your house but an oversized AC is as problematic as an undersized AC.

A smaller AC will have to work harder for cooling the house. The compressor will be on for a longer amount of time. This can lead to frozen coils and a faster rate of component breakdowns.

When we look at an oversized AC unit, it will cool the house more quickly and always short cycle. This will also lead to the wearing off of AC components and the AC not cooling.

Hire a technician to determine if your AC is of the correct size. In case your HVAC system is oversized or undersized, you will have no other option than to replace the unit with the recommended size for your house.


If your AC is not cooling, you should prepare to inspect different parts of your AC one by one because there are many causes of this problem. Begin by cleaning the air filters. If you find any inspection difficult, consult HVAC repair services Vienna VA to detect the problem and fix it.


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