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Why is Your AC System Constantly Running?

The warmer temperatures are finally here and you’re counting on your central air conditioning system to keep you cool and comfortable all summer long. But since you’ve turned it on, your AC is running nonstop and failing to provide the cooling comfort you need. Why is your AC system constantly running and does this mean you have a problem?

What’s Normal and What Isn’t?

When it’s really hot outside, it’s normal for a central air conditioner to run without cycling on and off as often. Running longer can be a positive thing because there’s decreased wear and tear on your AC system with less starting and stopping. However, if your AC system is consistently running for long periods of time with little effect on your home’s temperature, or there’s uneven cooling in your home or unexpected spikes in your electricity bill, you should call an experienced air conditioning professional to get to the source of your problem.

10 Common Causes of a Constantly Running AC System

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. Here are some of the most common causes of a constantly running AC system:

Dirty Evaporator Coil:  If you didn’t have your air conditioning system serviced before turning it on for the summer, the evaporator coil may be covered with dirt and debris. This can impede the cooling process and make your unit work harder to cool your space.

Frozen Evaporator Coil:  If your unit is running constantly and blowing warm air from the supply vents, it may have frozen up. You should shut it off immediately and contact the experts at Main Stream Mechanical to diagnose the problem and help you prevent further damage to your system.

Clogged Air Filter:  If your system’s air filter is full of dirt and debris, airflow is restricted, which impedes the functioning of your AC system. Without an adequate amount of air flowing over the coils, the system cannot remove humidity or cool the air to the set temperature, so it keeps running when it shouldn’t.

Overly-Restrictive Filter:  Even if your air filter is new, you could be using one that’s too restrictive for your system (i.e. one designed to remove pollen and allergens). For better airflow, consider installing a larger pleated media air cleaner at a MERV of 11 or higher (depending on design specifications).

Low Refrigerant Charge:  If you don’t have enough refrigerant in your AC system— likely due to a leak—your unit cannot effectively cool your home. In an effort to work harder, your system will keep running. If this happens, you need an experienced HVAC professional to find and repair the leak and restore the refrigerant to the correct level.

Faulty Thermostat:  If your thermostat isn’t working correctly, your system will not turn off when the set temperature is reached. Check your thermostat to see if your home’s actual temperature is below the setpoint. If it is, your thermostat probably needs replacing.

Leaky Ducts:  If you have older, worn, or damaged ductwork in your home, your AC system may be leaking cool air. If enough cool air escapes, the temperature will never reach the set point and your system will keep running.

Dirty or Blocked Condenser:  The condenser coils on your outdoor unit are regularly exposed to the elements. Over time, airflow can be obstructed by dirt and debris. A good cleaning by an HVAC professional will take care of this problem.

Blower Motor and Fan Issues:  When the blower motor isn’t producing enough air or the fan speed is too low, your AC system loses efficiency and will run too much. An experienced HVAC professional can adjust the fan speed to solve the problem. If your fan blades are dirty, it can also affect your system’s efficiency level. Again, your AC system may need a good professional cleaning.

Improper Unit Size:  If you’ve expanded or remodeled your home, it’s possible that your unit no longer meets your space needs. Have an experienced HVAC professional do a “load calculation,” which takes into account the design, layout, and size of your home, among other conditions. The HVAC professionals at Main Stream Mechanical provides this service at no charge.

With annual AC system maintenance, the majority of these problems can be prevented.


AC System Maintenance and Service in Massachusetts and Southern New Hampshire

If your AC system is constantly running, or you need help finding a system that will meet the needs of your home and family, contact the professionals at Main Stream Mechanical for your free consultation.

We travel throughout the Greater Newburyport, Boxford, Topsfield, Bedford, Lexington and Arlington areas in MA and the Greater Derry, Seabrook, Stratham, Dover, Exeter and Rye areas in NH. See our full-service area list for towns not noted. For a no-obligation consultation, call us today at (978) 834-0849.


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