How to Fix Common AC Problems

Trouble with your AC unit doesn't always have to mean an expensive repair bill. In many cases, there are simple strategies you can use to troubleshoot problems associated with your system. Below is a list of the most common AC problems homeowners encounter. Apply the solution that matches your need, and with a little luck, your AC system will be up and running when you need it most.

Problem 1: Your Air Conditioner Isn't Cooling Your Home

This basic problem can be caused by several different factors. To fix it, first check to see if your thermostat is set to "ON" or "AUTO." If your system is set to "ON" it means the fan — not necessarily the cooling system — is on and the fan will blow air regardless of if the air is cool or not. Changing the setting to “AUTO” will ensure that the system fan only blows when the air conditioner is actively cooling.

If your home's system is set to "AUTO," the problem could be caused by a dirty air filter, which blocks cool air from traveling through your system. Follow these guidelines for choosing the right air filter for your home and how often you should change the air filter, and your AC system will be able to breathe easier.

Problem 2: Your Air Conditioner Turns On and Off Frequently

This frequent problem is commonly referred to as short cycling. In some cases, an issue of short cycling may be caused by something as simple as the placement of your thermostat. If the thermostat is situated near a vent, the system may believe the air in the entire home is the same temperature as the air coming from the adjacent vent. In this case, the thermostat must be moved. Another common cause of this problem is a dirty air filter, which must simply be replaced.

If neither of these fixes solves your problem, your system's rapid on-off pattern could be caused by leaking refrigerant. In this case, it's best to seek help from a professional air conditioning company. The worst-case scenario is if the problem is caused by an oversized air conditioner. Air conditioners should be carefully sized to match the spaces they’re meant to cool, and if they’re too large, they can cool down spaces too quickly. That might sound like a good thing, but when cooling is too rapid, three problems occur: 1) the air conditioner can’t properly dehumidify the home, leaving it feeling damp and clammy, 2) the unit short cycles constantly, wasting energy, and 3) the frequent starts and stops increase wear and tear on parts, leading to more repair bills. In cases of an air conditioner mismatch, it’s often the case that the only effective solution is to replace the unit with one that is properly sized.

Problem 3: Your Air Conditioner Isn't Turning On

What if your system isn’t turning on at all? The good news here is that it may be possible to solve this problem without having to purchase a new unit. For starters, check your circuit breaker box to make sure your air conditioner breaker switch hasn’t been flipped. If it has, you can turn it back on, but you should call an HVAC professional if the breaker trips again, as this is a sign of a more serious problem. If it’s not the breaker, check the thermostat to make sure it is set properly. If it is, you can also lower the thermostat an additional 5-10 degrees to see if this starts your AC unit. Finally, if none of these options work and your system has a condensation pump, check the pump to see if it is full. Some units are programmed to shut down automatically once the pump is full and your solution may be as simple as replacing or cleaning the pump.

Problem 4: Your Air Conditioner is Leaking Water

Air conditioners produce condensation in the process of cooling a home, and most models are designed so that the condensation will drip into a catch pan and flow through a drain tube to the outdoors. Over time, the drain tube can become clogged with algae growth, accumulated impurities from the water, or even insect nests closer to the outlet. When the drain line is completely blocked, water can back up into the catch pan and overflow. This can create a big mess, especially if your AC unit is installed in the attic and will drip down into the rooms below.

If this happens, shut off your air conditioner and locate the drain pan. In the short term, you can use a cup or sponge to bail out the catch pan to help avoid an even bigger mess, but you need to clear the drain line to fully fix the problem. Use a long, flexible pipe cleaning brush of the appropriate size to clean the drain line from both ends. If you have a portable air compressor, you can also use that to blow the line clear from the air conditioner side. Once the line is clear, pour a few cups of white vinegar into the catch pan to help prevent future clogs, and continue to do so about every other month during cooling season.

If your AC system is not operational and you’ve tried all the troubleshooting suggestions above, then the problem is likely larger than you are able to solve on your own. If this case, it’s time to seek the help of a certified technician. When you hire your technician, ask questions about your home's AC system and why it wasn't functioning properly. Learning more about your air conditioner and how it works will help you better troubleshoot any future AC problems.