Few things are worse than a malfunctioning air conditioning system in the sweltering summer heat. There are a few ways to troubleshoot your HVAC system if your AC is not blowing cold air. Of course, it’s always wise to contact an HVAC professional for service and repairs. Identifying the potential root cause of the problem and communicating any findings to your contractor helps. This information enables better preparation for repairing your unit quickly. Plus, address any problems as soon as possible. Why? Because a broken air conditioning unit is not only an inconvenience, but possibly a major health concern if temperatures soar.
There are some relatively common reasons your AC may have stopped working, including:
- Power issues
- Thermostat issues
- Clogged filter
- Ice buildup
- Clogged drain
- Dirty compressor
- Condensate airflow switch
- Low refrigerant levels
There is hope. Fixing some issues on your own remains an option. Plus, most are easily repaired by a qualified HVAC technician.
Power issues
It might sound basic but if your AC is not blowing air, check to ensure that it’s plugged into the outlet correctly, and that the power cord is still intact. If the outlet and cord are fine, it could be an issue with your electrical panel. Air conditioners require large surges of power, and your unit might have blown a fuse or tripped a breaker. Some units have overload switches built-in, so make sure you check this as well.
Thermostat issues
If all looks good on the power front and your AC is still not blowing cold air, it could be that the thermostat on your unit isn’t set at an appropriate temperature. Try turning the dial down all the way, or pushing the buttons to the lowest setting and see if that trips the unit to run. If you’re able to, check to ensure all wiring into the thermostat unit (and any batteries, if applicable) are connected properly.
Clogged filter
Some AC units have a built-in mechanism that shuts the unit down if the filter is clogged. This is to prevent damage to the motor and overheating. It could also be that the filter is so clogged that it’s not allowing for adequate airflow. Check your unit’s filter and clean or replace it if necessary.
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Ice buildup
There are a couple of reasons for ice buildup in your AC — dirty coils or filters resulting in poor airflow, or a lack of refrigerant. Try cleaning your air conditioner’s filter and the coils to see if improving the airflow fixes the problem. If there is ice buildup, you’ll need to run the unit with just the fan in order to melt it off. If that doesn’t get the unit blowing cold air again, it could be refrigerant levels are low (see below).
Clogged drain
Air conditioners remove moisture from the air, with the water typically draining out a hose or drain pipe which can become clogged with algae, ultimately causing the unit to shut down. This is an important safety feature that prevents water from backing up into your home or the unit and causing damages. The piping can sometimes be replaced, but can also be cleaned with a mild bleach solution.
Dirty compressor
Part of your regular maintenance should be cleaning the area around your compressor and covering it for the winter. Over the year, leaves, dirt, and other debris can build up and stop the unit from running properly. While some homeowners handle compressor cleaning, enlist professional help for the best results. This ensures your unit receives proper cleaning and the appropriate maintenance. Always ensure the unit is shut off before beginning any work.
Condensate airflow switch
Some air handlers contain an integrated safety float switch that trips and shuts off the unit when the drain pipe backs up with water. If you check and find that the switch has tripped, it must be reset after the condenser drainpipe has been cleaned.
Low refrigerant levels
Contrary to popular belief, coolant doesn’t go bad or deplete; a common reason for a lack of cold air is often a refrigerant leak. Slow leaks can cause refrigerant levels to drop over time, which requires a check of the lines, and a recharge of the system in order to get it blowing cold air again. This should be done by a professional due to the complex nature of cooling systems and the chemicals involved.
Depending on the age of your unit and the level of work involved, consider updating your system. For example, upgrading to a new system makes sense for a more reliable model. An upgrade makes a wise investment in certain circumstances, such as:
- systems older than 10+ years old.
- consistently experiencing recurring problems.
- fixes that cost more than you’re comfortable paying.
As with all things in life, the old adage “an ounce of prevention is worth a pound of cure” is true when it comes to your air condition system as well. By having a professional technician perform annual inspections and staying on top of any maintenance issues, you can help to avoid any potential AC outages.
A licensed HVAC technician ensures your system remains running in tip-top condition. Plus, they inspect the system so it remains compliant with any local and national building codes. When in doubt, enlist the help of a qualified professional rather than risk damaging your system further by attempting DIY repair.