An air conditioner is a complex system, so when your air conditioner isn’t quite working right or isn’t working at all, there are a lot of potential causes for the problem. However, while the possibilities may be nearly endless, there are a few common causes that we see over and over again. And some of them are things that you can check and potentially correct or prevent on your own.
Dead Batteries in Thermostat
If your air conditioner isn’t coming on, one of the first things to check is whether the thermostat is working. You can try switching the fan from AUTO to ON to see if the fan will come on. If the fan turns on, then you know the thermostat is at least sending a signal to the AC unit. But if the fan doesn’t come on, then it may mean that the thermostat needs new batteries. Try replacing the old batteries with fresh ones, and you might save yourself a service call!
Dirty Filter Blocking Air Flow
Another common cause of many air conditioner problems is a dirty intake air filter that’s blocking the flow of air into the system. When your air conditioner can’t get enough air flow, it will struggle to cool your home. Decreased air flow can even cause the coils to freeze over. Make sure you have a clean air filter, and replace it monthly. If the coils freeze, turn off the air conditioner and allow it to defrost completely before turning it back on. And make sure that before you turn it on, you have a clean air filter in place. Again, regularly replacing your intake air filters is a great way to cut back on the number of service calls you’ll need to make!
Clogged Drain Line
If there’s water collecting around your air conditioner or if there’s a musty odor coming from your vents, you may have a clogged drain line. When your AC runs, condensation collects on the evaporator coils, then drips down into the drain pan and runs out of the unit through the drain line. If the drain line gets clogged, then the water builds up and can overflow the drain pan. Plus, if there’s constantly water sitting in the drain pan, mold can begin to grow, causing that musty odor. A licensed HVAC technician can clear the clog out of the drain line and clean up any mold that has grown.
Coils Need Cleaning
The coils in your air conditioner can get dirty and corroded over time. They can even get mold and other microorganisms growing on them due to the moisture from humid air. When the coils are dirty, they cannot exchange heat as effectively, which means that your air conditioner will have to use more energy and probably won’t keep you as comfortable. It can also lead to your coils freezing over. Having your air conditioner’s coils checked and cleaned as necessary by a licensed HVAC technician is an important part of regular preventive maintenance.
Electrical Control Failure
The electrical components and connections in your system can get worn out or corroded, especially if you have an oversized system that short-cycles (turns on and off frequently rather than running steadily for longer periods of time). One of the most common culprits when air conditioners break down is a burnt-out capacitor. Again, this is something that should be checked during regular preventive maintenance by a licensed HVAC technician. You should never attempt to work on the electrical systems of your HVAC yourself.
Dirty or Leaky Ductwork
If your air conditioner seems to be running fine, but you’re just not getting even, effective cooling throughout your home, you could have a problem with the ducts that are carrying the air from your AC unit throughout your home. Ducts that leak can waste a whole lot of cooled air—and a whole lot of energy! Ducts can also become clogged with dust or debris, keeping air from moving through them like it should. If there’s one room of your house that never seems to get cool, you should definitely have an HVAC technician check the ducts leading to that room for blockages. We’ve found everything from stacks of magazines to dead possums stopping up the ductwork in homes!
When an air conditioner is running and air is flowing, but that air just isn’t very cool, the most common cause is low refrigerant. But contrary to popular belief, air conditioners don’t “use up” refrigerant when they run. If an air conditioner has low refrigerant, it generally means that there’s a leak in the coils or lines. These leaks can be invisible to the eye, so you’ll need a licensed HVAC technician to test your system for leaks, seal any that they find, and then recharge the refrigerant. If they don’t fix the leaks first, you’ll just end up with the same low-refrigerant problem again later.