Why Is My HVAC Not Cooling?

Estimated reading time: 6 minutes

Summer is right around the corner. Have you prepared your home for the hot Texas Weather? If not, then now is the time to schedule an HVAC inspection or maintenance. You may discover that there is a problem with your system. One of the most common HVAC problems is temperature control – most specifically, you turn on the system, but your HVAC is not cooling.

Today’s HVAC systems are complex. Unfortunately, it can be hard to diagnose your system and identify why cool air is not coming out of the vents. Below we explore some of the most common causes of HVAC failure and why your system may not produce cool air. If you have any further questions or need to schedule an HVAC repair in Dallas, TX, contact Energy Attic today.

Leaky or Clogged Air Ducts

Air ducts are typically routed in isolated areas in your attic or walls. The design makes them difficult to reach and even more difficult to assess. As a result, problems such as clogged, leaky, or damaged air ducts can be nearly impossible to diagnose. Air duct leaks can be subtle. However, they can release cold air into the attic instead of cycling it through the house.

If you notice a reduced airflow and a lack of cool air, your air ducts may be clogged. Neglected air ducts can suffer from dust buildup. Or, an object may be lodged in the ducts, preventing the cool air from flowing freely through the system.

Old, Dirty Air Filters

If you live in your house long enough, you will eventually forget to change the HVAC air filters. Old, dirty air filters can inhibit airflow. The dirt on the filter eventually builds up and blows through the air conditioner, making it dirty. A dirty HVAC system operates far less efficiently, causing your heating and cooling bill to skyrocket.

A dirty system causes the HVAC coil to freeze up. Once a layer of ice covers the coil, there is nowhere for the air to flow. The fan may continue to run, but no cool air will circulate through your home. It doesn’t take long for you to notice the lack of airflow due to high humidity and even higher temperatures.

HVAC Fan Failure

HVAC fans are impressively resilient, lasting for several years without needing a replacement. However, even the most well-built fans will eventually wear out. Common fan problems include:

• Faulty motor
• Dirt buildup
• Degraded lubricant
• Broken blades
• Damaged capacitor or contactor
• No power to the unit

Blown Breaker, Capacitor, or Fuse

When your HVAC system breaks down, one of the first things an HVAC contractor checks is the power source. In this case, they will check the breaker, capacitor, or fuse in your electrical system.

A blown fuse or breaker indicates that the HVAC requires more power than the breaker can handle. If the problem persists, you may need to upgrade your wiring or breaker box to accommodate your HVAC. Or, the problem may be as simple as replacing an outdated fuse. 

Thermostat Malfunction

Perhaps one of the most difficult HVAC problems to diagnose is a thermostat malfunction. While the device is simple to operate, various issues could cause it to stop working. Some of the most common issues include:

• Poor location in the house
• Dirty, old, or unbalanced thermostat
• Weak power source (bad wiring or dead batteries)
• Improper installation or calibration
• Programming defects

When the thermostat malfunctions, your best option is to contact a licensed HVAC contractor who can assess the problem and offer the appropriate solution. You are more likely to have long-term results with professional AC repair.

Clogged HVAC Drains

Modern HVAC units contain sensors that alert you when a blockage in the HVAC line prevents it from draining. The easiest way to tell if the HVAC drain is clogged in older units is to look at the drain pan. The pan should never be full of water. If it is, there is a drainage issue (Note: check the drain pan every time you change the HVAC filter).

Drain pipes are small enough to allow muck and algae to build up and block condensation from the unit. If you neglect the drain, the blockage is inevitable due to the minerals in the water. Once you unclog the drain, you should instantly notice a difference in the AC temperature. Cool air should circulate through the house within minutes.

Low Refrigerant Levels

It’s fairly easy to tell if your HVAC system is low on refrigerant. Three common signs of low refrigerant levels include:

• The HVAC is blowing hot, humid air.
• There is ice on the refrigerant line.
• There is a distinct hissing or bubbling sound coming from the unit.

State laws and EPA regulations may prohibit you from adding refrigerant to your HVAC system on your own, depending on what type of system you have and what type of refrigerant the system requires. If your system needs refrigerant, there may be a leak in the refrigerant line. So, you are better off hiring a professional to do the job. 

The Coil Needs to Be Replaced

There are numerous signs that the evaporator coil is damaged and needs to be replaced. For instance, is your HVAC unit starting and stopping constantly? Or does it not turn on at all? You may also hear unusual noises coming from the HVAC unit. A refrigerant leak may originate with a bad coil. And, of course, the HVAC unit is blowing hot air. 

One of the best ways to prevent a coil from going bad is to schedule routine HVAC maintenance. A routine inspection allows a contractor to identify small issues before they turn into larger, costly problems.