NYC Metro Area’s HVACR Blog

Commercial HVAC, Residential HVAC

Your AC Running Constantly is Trying To Tell You Something

Share:

Remember the Grinch, slowly driven mad by the Whoville Christmas celebrations with all that NOISE, NOISE, NOISE, NOISE? That’s how you start to feel when your AC is running constantly. It’s annoying enough to turn anyone into a Grinch.

All that noise from your air conditioner is trying to tell you something! And the problem will only get worse if you don’t address it.

What that AC running constantly is costing you (besides your sanity)

The noise is not the only thing you have to worry about when your AC is running constantly. When your air conditioner runs throughout the day and night without shutting off, or if it cycles on and off continuously, there are several causes for concern:

  • Wasted energy. When your AC’s running constantly, it’s also running up your electric bill.
  • Wear and tear on the parts. If your sanity is being strained, just imagine what your AC running constantly is doing to your air conditioner’s parts.
  • Impending breakdown warning! Your AC running constantly tells you that something is not working right, and the problem will get worse if you don’t take care of it. Eventually the noise will stop, but so will your air conditioning.

Common causes of AC running constantly

At this point in the season, the weather is still cool enough that you can rule out one possibility: that your AC’s running constantly because there’s an extreme amount of heat to remove from the air. That only happens when the temperatures approach triple digits outside.

So what else could be wrong? Here are 8 possible causes of your AC running constantly:

1. Frozen evaporator coil.

If your unit is blowing warm air from the supply vents in addition to the AC running constantly, it may have frozen up. this often happens when the system has issues due to neglected maintenance. Turn the air conditioner completely off, and call in a professional right away to diagnose the cause and prevent further damage to the system.

Related Article: AC Troubleshooting: FROZEN HVAC System? Don’t “Let it Go!”.

2. Condenser and/or evaporator coils need cleaning.

Have you had your air conditioner serviced yet this spring? If not, the coils may be covered with dirt and debris, impeding the cooling process and making the unit work harder to cool your space. Which means you’ll hear the AC running constantly.

Both the evaporator coils in your indoor unit and the condenser coils in your outdoor unit need to be cleaned because they are exposed to outdoor pollution and indoor dust and contaminants. The coils can’t do their jobs when airflow is impeded by dirt and debris, accumulated leaves or even animal or insect nests. A good cleaning using professional products and tools will take care of this problem.

Related Article: AC Coil Cleaning: How to Tell When You Need It.

3. Air filter issues.

When your system’s air filter is clogged with dirt and debris, or if you’re using a filter that’s too restrictive for your system, the flow of air is impeded. Without enough air flow, it can’t remove humidity and cool the air to the set temperature, so your AC’s running constantly when it shouldn’t. Change or clean the filter to remedy this problem.

4. Leaking refrigerant.

The refrigerant is the substance flowing through the AC’s coils that actually removes the heat and humidity from the air in your space. When the coils develop holes or cracks, refrigerant leaks out of the system. As the refrigerant charge decreases, it becomes harder and harder for your system to cool the space. As a result you’ll hear your AC running constantly but not working as well. To correct this problem, you need an experienced HVAC service professional to find and repair the leak and restore the refrigerant to the correct level.

5. Faulty controls.

If your AC is running constantly and the space is colder than it should be, you might have a faulty thermostat. If so, your AC unit doesn’t know to turn off even when the desired temperature is reached. Check your thermostat to see if the actual temperature in the space is below the set point. If it is, there’s a good chance that the thermostat may need replacing, or it might just need a new battery.

6. Blower motor and fan issues.

If your blower motor is not producing enough air for your system, or the fan is running at a low speed, that can cause the system to lose efficiency and keep the AC running constantly. Your HVAC technician may be able to adjust the fan speed to solve the problem, or replace it if necessary. A layer of grime on the fan blades can also slow it down, so you may need a good cleaning.

7. Air leaks.

All that cool air your system is producing might be getting sucked out through walls, doors or windows with poor insulation. Or, if you have holes in your ductwork, the cool air gets lost in the crawl spaces and never reaches the spaces where it’s needed. That keeps your AC running constantly, fighting a losing battle to get the air down to set temperature.

8. Load changes and wrong-sized systems.

Have you recently renovated your space, rearranged the layout, or changed the usage of the space? If you’ve done so without updating your air conditioning and ventilation systems, it’s possible that your AC’s running constantly because it’s no longer adequately sized for the needs of your space. Bring in a certified HVAC professional to do a load calculation, taking into account the design, size and cooling requirements of your space, as well as windows and sun exposure, insulation and more.

How to fix it once and for all

The good news here is that almost all of the common causes of your AC running constantly can be fixed (and prevented for the future) with regular AC preventative maintenance.

Before you turn your system on for the season, call in an HVAC professional to perform a detailed inspection and maintenance.

When your system is running like it should, that annoying noise of your AC running constantly will be nothing more than a soothing purr. It’s enough to make your heart grow three sizes!

Related Article: 8 Ways AC Preventative Maintenance Keeps the Repairman Away.


Poor HVAC maintenance is hurting you in more ways than you realize. To find out more, take a look at our free guide to Calculating the Hidden Costs of Poor HVAC Maintenance.
Get the guide to understanding your HVAC System's hidden costs.