Nothing feels better than crisp cool air on a hot summer day. But this morning, you woke up and noticed that your air conditioning isn’t working; this can be frustrating. If you aren’t sure why your AC isn’t working, then we are here to help. Here is a list of reasons your HVAC system might not be blowing cold air. These are the most common, and they will give you some direction on whether to call a repair tech. This checklist isn’t exhaustive, nor is it meant to be in a specific order, but it will give you some direction on what next steps to take.
Is Your Air Vent Closed?
You’d be shocked how many service calls are cut short by simply checking your air vents. This is, without a doubt, the most straightforward explanation for why and how to fix this issue yourself. Examine your air vents and make sure they’re open. If there’s dust or debris buildup, use a brush or vacuum to remove it.
Now that your vents are clean, you want to measure the airflow coming from the vent. You can use either your hand or a lighter to test for this. Hold the lighter to the vent and back away until you can’t see the flame flicker from airflow anymore. Ideally, you want to feel the air from one end of the room to the other.
If you tested your vents and the airflow is good, you know that isn’t the problem. The air should have a good flow and come out cold; if it’s not coming out cold, then look at other possibilities.
Check Your Breakers
A strong electrical surge might damage your circuit breakers, known as tripping your switches. Check your circuit box to see if a switch is flipped. It should be labeled “AC” or “HVAC.” A flipped switch is not generally the cause, but it can happen. Examine both the breaker box and the outside panel for signs a circuit was switched off. If it is, switch it back on and check for cool air again.
Your Thermostat is Broken
The thermostat is the device on the wall that controls the HVAC unit. If it’s not working correctly, your house may not cool as expected. Depending on the type of thermostat you have, simple things like the power going out can reset the device’s calibration. Check that the thermostat is set to ‘cool’ and not just ‘on.’ The ON setting indicates that the fan is on, not the AC; switch them.
Thermostat failures are subtle, and there aren’t noticeable signs outside of the house not cooling (or heating) properly. If you think your thermostat is the problem, check the thermometer on the thermostat. Does the temperature on the thermometer match the temperature of the thermostat setting? If not, you’ve likely found the cause of your cooling discrepancies.
Dirty AC Air Filter
When was the last time you changed your air filter? If Saturday morning cartoons were still a thing, it might be time to change it. A dirty or clogged air filter can be a common cause of your AC not blowing cold. This is because the clogged dirt on the filter inhibits airflow. You must maintain all parts of your HVAC unit if you want it to work as designed. We recommend that you change your air filter at least every six months. Choose one from a reputable company designed to fit your unit. If you’re not sure what type of filter you need, we have a tool to help you find one based on your unit and needs.
Your Condenser Outside is Broken
Many homeowners overlook the HVAC system outside – the air condenser. Your air condenser is the box-shaped unit outside of the house. Many homeowners, possibly yourself included, allow grass and debris to build up around the unit, compromising airflow and reducing its overall effectiveness. Dust, dirt, and debris can build up inside the unit, causing it to stop working correctly as well. This can be easily avoided by checking the unit annually.
There are already plenty of chores you are doing around the house, but cleaning your air condenser will likely be a new one for you. Make sure that you’re regularly maintaining the lawn around your unit’s condenser. Use a mower or weed-whacker to keep grass, bushes, etc., from around the condenser. Also, consider reducing the number of trees around the unit as well. This will prevent anything from potentially falling in. Once you’ve tamed the foliage around your condenser, you should rinse it once a year to keep it running smoothly.
Warm Air But Frozen Air Handler
One last mechanical part we want to talk about is your AC air handler. This part is a little heavy on technical info, but it’s something you really should know. Your AC unit has two primary jobs: cooling your home and dehumidifying your home. It does this by passing the air over the evaporator coils. These coils are extremely cold due to refrigerant (freon). The water vapor is chilled and becomes denser and will sink and stick to the evaporator coils. The air that passes through the other side of the evaporator coils is now “dehumidified” because the water vapor is removed.
When your air conditioner is working correctly, water buildup drops into the condensation drain pan below once the evaporator coil is full. It’s a delicate balance, and other system malfunctions can cause this process to operate improperly.
Water on the coils will sit for too long if there is no adequate airflow. If the water stays on the coils for too long, it might freeze! Even a minor ice layer is sufficient to cause an increase in the ice accumulation frequency, resulting in a block of ice in a little amount of time.
The only sign you’ll have is that your AC isn’t working correctly. Ice prevents the air from passing over the refrigerant at the proper levels and will lead to warmer air in your home. If your AC is frozen, turn it off and allow about 24 hours for it to defrost.
Dirty Air Ducts
If you’ve already replaced your air filter recently, you should make sure that your ducts are clean. Though unlikely, dirt can be shaken loose from airflow and clog components of your HVAC unit, including the air filter you just replaced. Dirty air ducts usually are not the reason your AC doesn’t work but can be one factor that leads to it not working. This is more of a preventative step instead of a diagnostic one.
Home insulation plays an essential role in your home’s overall heating and cooling efficiency. If your home isn’t properly insulated, then air will leak out (or in). This will cause an inconsistent temperature in your home. Insulation is a difficult thing to diagnose without the proper tools, but here are some simple tests you can do yourself.
- Check Air Duct Insulation
- Air ducts, even ‘insulated’ air ducts, should have outside insulation to prevent air leakage. Take a look at the ducts around your house (the square sheet metal pipes) and see if they have insulation around them. If they don’t, you should look into having some installed. Your local air conditioning company should be able to assist.
- Check The Joints
- Joints or junctions of air ducts could be sources of air leakage. Hold your hand up to the joints and see if you feel any air coming out. If you do, call a technician.
If you’ve gone down this list and still can’t get your AC to work, it might be time to call a technician. Find a qualified and insured company to do the repairs. Frequently, they may give you a free estimate before completing the work. Using this list will cut down on the time the tech will use to diagnose the problem and could save you money.