4 Major A/C Problems & What to Do

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Photo: Creative Commons

This post was written by guest blogger Molly Chen of Winters Home Services.


What’s wrong with my A/C?

If you came here, you might be asking this question because your A/C won’t turn off, the air isn’t cold enough, or the airflow seems weak.

Unlike most heating systems, air conditioners have more complex mechanical systems that demand a wide variety of parts working correctly. Central air conditioners are designed to meet a certain “load” on the house and need a certain amount of refrigerant or freon to work. They also need good air flow across the coils. Should any of these things go wrong, the system will not work properly.

Here are 4 major issues that can go wrong in an A/C and a few solutions for each. Since air conditioners are more complicated and problems might not be easily resolved, we strongly recommend homeowners call a professional.

  1. My Central A/C Has Weak Airflow

Sometimes the air handler seems to be working fine, but the air coming out of the vent is weak.

Solutions: a dirty air filter can block return airflow, preventing the A/C from supplying air to your home. Some systems have two air filters, one at a return grille and one at the air handler inside. So check your air filters, and also check the vents to make sure they are open. Sometimes, homeowners close vents and registers in unused rooms to save money, but this can cause problems. Lastly, be sure to remove any furniture or curtains that are blocking the registers.

  1. My A/C is Blowing Warm Air

The thermostat shows that the unit is on, but it’s blowing warm air instead of cold. Most of the time, this means your system is low on refrigerant, which is more commonly known as freon (which was actually a brand name for a refrigerant that was banned years ago!).

Solutions: Be sure that your air filter has been changed. Sometimes all it takes is a dirty air filter to cause this issue. Also, check your outside unit to make sure it’s not dirty. Why? When a condenser (the outside unit) has dirty coils, it has a hard time releasing heat since the dirt is insulating the coils from releasing heat to the outside air.

Cleaning the coils is easy. You can do it yourself or call an HVAC contractor. To clean it yourself, stop by your local Home Depot or Lowes for a coil cleaner, wear gloves, and follow the instructions on the cleaner. Be sure to turn your outside unit’s power off! When you’re done, turn the system back on and voila! You have a clean condenser. Or you can call an HVAC professional, which is probably the best option, because they can check your unit for any other problems. And if it’s the most common problem – lack of freon – only an HVAC professional can check that.

  1. The A/C system is constantly running and won’t turn off

A lot of people automatically turn to the solution of adding freon, but there are actually multiple causes.

Solutions/questions to ask:

  • When was the last time you had your evaporator coil cleaned?
  • When was the last time you had your air filters changed? We recommend homeowners change the A/C air filter every month during the summer.
  • When was the last time you had the system “charged”?
  • Is there about 17 degrees difference between the supply air and the cold air coming out of the vents? If so, this is normal because it’s so hot outside that your system can’t keep the temperature up. Sometimes, all it takes it a properly-sealed door and window.
  • Set your thermostat a few degrees higher.
  • Is your system is undersized?

Bottom line is, there are a lot of factors that could be the cause of this issue. The best thing to do is have a professional run diagnostics and determine the real cause.

  1. My refrigerant/freon is leaking

Sometimes homeowners can detect the refrigerant leak themselves. Most of the time, you need a professional to test it, usually with an electronic leak detector and various leak detection mixtures. But what causes the leak?

  • Bad installation: it is so important to have a good technician installing your system. Incomplete brazing can lead to slow leaks that will happen 5 years after the installation. So don’t always go by the cheapest company, go by the BEST company with great craftsmanship, great reviews and a warranty.
  • Acid: the type of acid called “formic” is a naturally occurring acid that comes from the ground and etches the copper coil, causing microscopic cracks in the copper.

Solutions: apply a leak seal treatment or replace the leaky component if the product is under warranty. However, sometimes an empty system might hold hidden damages and will require more than a simple recharge. Most of the time, if the compressor is dead, a repair will not do it justice. See our article on “4 Signs Your Central AC system is Failing” to determine your investment.

Have you tried all of the above and your system still isn’t working properly? Don’t hesitate to call a trusted professional to get your system back in tip-top shape! (For tips on finding a good contractor, check out EnergyStar.gov’s list here.)


This blog was written by Molly Chen of Winters Home Services in Cambridge, MA. For more, visit their website or blog, or follow them on Twitter!

About us

“The CRT Tipster” is an HVAC tips and news blog owned by Controlled Release Technologies, Inc. We are a chemical manufacturing company in Shelby, NC, that creates products for HVAC maintenance and more! Find us at cleanac.com, or call us toll free at 800-766-9057.

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