7 Reasons Your Air Conditioner is Running but Not Cooling Your Home

June 10, 2015

Does your air conditioner run all day and yet your thermostat still reads above 80 degrees?

While longer run times are better for energy efficiency, NEVER shutting off is not a good thing for your AC.

Here are the top 7 reasons an air conditioner may run constantly without cooling your home:

Dirty air filter

When was the last time you changed your air filter? You should check it every month and change or clean it when it’s dirty.

If you don’t, you’re basically suffocating your air conditioner. Dirty filters restrict the airflow to you AC. And less airflow into your AC means less cool air makes its way into your home, which means it takes your air conditioner a long time to do its job.

Or, in some cases, it can’t do its job.

Vents are closed/blocked

Another way you can suffocate your air conditioner is by closing or blocking vents. Contrary to what you may have heard, you shouldn’t close vents in unused rooms.

To understand why closing vents costs you money, let’s back up for a second and describe how your air conditioning system distributes air in your home:

  1. The inside unit has a blower that pulls in air from your home via return grilles. 
  2. The AC cools that air. 
  3. The blower pushes that cooled air out the supply vents (the thing homeowners try to close).

Keep in mind: That blower is designed to push against air up to a maximum pressure. But if you close a vent, you’re increasing pressure in your duct system.

This causes the blower to keep running but at a lower speed. So now you have less air coming out supply vents, making it take much longer to cool your home.

Dirty outside AC unit (condenser)

Your AC absorbs the heat from your indoor air and deposits it outside. To get rid of the heat, the outdoor unit (the condensing unit) has a fan that blows air over the warm refrigerant line.

But if the condenser is dirty (like filled with grass trimmings, dirt and other debris), it can’t get rid of the heat very efficiently. This creates a major problem for your air conditioner because if it can’t get rid of the heat, it can’t cool your home well.

Low on refrigerant

Refrigerant is the lifeblood of your air conditioner, so if there’s not enough, your home won’t be cooled very well.

Normally, your air conditioner should never need more refrigerant. It’s not “used up” like gas in a car; it’s simply recirculated throughout your AC system.

However, air conditioners can develop refrigerant leaks that need repairing by a professional AC tech.

Note: If a contractor tells you you’re low on refrigerant, make sure they also check for and fix the leak! Otherwise, you’ll need more refrigerant again soon. And that stuff isn’t cheap.

Leaky air ducts

Your air ducts carry your cooled air into your home. If they’re leaky, your AC may be working perfectly, but all the air (or at least a big chunk of it) is cooling the your attic or crawl space instead of your home!

A really drafty home

Your home may simply have too many air leaks in it. Leaks around doors, windows, electrical outlets, vents and more let hot air into your home.

If your home is especially leaky, your air conditioner may not be able to cool your home as fast as the air leaks out.

An air conditioner that’s too small

Finally, your air conditioner may be running but not cooling your home because it’s too small. An undersized unit can’t cool your home because heat makes its way into your home faster than the AC can remove it.

This is likely an installation problem. The AC installation company probably didn’t do a proper Manual J calculation to determine the correct size air conditioner for your home.

Or, if you’ve closed in a porch or added another room to your home, you may simply need additional cooling capacity now (perhaps, a bigger air conditioner).

Want to get rid of this annoying problem?

Santa Fe Air can troubleshoot and fix your air conditioner problem. And we serve the entire Kansas City metropolitan area. Just contact us to get started!


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