April 28, 2017

St. Louis man checking air vent

My air conditioner is running constantly– what’s the problem?

Your air conditioner can be expensive to run, but it’s a necessity in the hot summer months. While it is a necessary expense, if your air conditioner is running constantly, something may be wrong. Our St. Louis HVAC technicians explain the reasons your air conditioner might be running constantly.

Why your air conditioning is running constantly

Here are some common reasons why your air conditioner may be running nonstop:

Your air conditioning unit is too small

If your unit is too small to sufficiently cool your home, it will need to run all the time to achieve the desired temperature. This means that the lifespan of your unit will be reduced as it is in use more than it really should be.

Your air conditioning unit is too big

If the unit is too large, the moisture will not be removed from the air. This results in short run times and uses a lot of electricity.

Your ducts are the wrong size

It’s important to have the right size ducts for the size of your unit. If the size is incorrect, your unit will likely not work as efficiently as it should.

According to our HVAC technicians, an incorrect size unit or ductwork accounts for around 75% of problems. Once you’ve ruled out these most common of issues, the next things to check are…

The filter

Filters get dirty over time and this affects the amount of cool air your unit can produce. Check your filter. A dirty filter can easily make your unit break down. Clean then once a month and replace them every six months.

The conditioner coils

Dust, dirt and pet hair can all clog up your conditioner coils and reduce performance. It’s a good idea to have a St. Louis HVAC company service your unit on a yearly basis. They will check your coils and clean them if necessary. They will also check the hard to reach evaporator coils for you.

Your thermostat

It could be that your air conditioning is simply not turning off when the required temperature is reached due to a problem with the thermostat. You can put a thermometer near your unit and see if the unit turns off as it should when the set level is reached. If it does not then a faulty thermostat could be the cause of your problems.


A broken seal, or a lack of sufficient insulation could also be the issue if your air conditioning is running constantly. Adding extra insulation and making sure you don’t have any drafts in your home could really help to save you money on both your air conditioning and your heating.

The unit has reached the end of its life

If you’ve worked through all these checks and nothing seems to be the cause then it may just be that your unit is simply old and has become very inefficient. It’s time to buy a new one. This will save you money in the long run! Contact Scott-Lee Heating Company today to learn more about your options.

Call (314) 200-0788