Why is My AC Blowing Hot Air?
TechXpert verified by Ken Kontra
If your AC is blowing hot air, you may be dealing with a maintenance issue, a damaged part, or something as simple as an incorrect thermostat setting. There are many parts that keep your AC working, so when the air temperature is off, there’s a good chance one or more pieces are malfunctioning.
Quick Fixes to Keep Your Cool
When summer rolls around, you’ll want a functioning AC to keep you cool as the temperature spikes outside. If your AC isn’t blowing cold air (or any air at all), there are a few things you can check yourself before considering whether there are damaged parts in the unit.
Sometimes the answer is right under your nose. Your thermostat fan setting plays a big role in comfort and cost: When your thermostat is set to “on”, it’s constantly running your AC indoor blower, even when your air isn’t being cooled. The upside of this is a balance in temperature between rooms in multi-level homes. The downside? Your system won’t dehumidify as well, because the condensation and water will be reintroduced to the air from your ductwork.
Keep in mind that the “auto” setting will run the blower only when there’s a need for cool air, plus it can help reduce humidity levels (the fan only runs during a cooling cycle, which dehumidifies), so you’re using less electricity.
Remember that in order to cool the air, it has to circulate, and that’s where a clean filter can help: the air filters in your AC keep your air clean and flowing freely. If they collect too much dust or debris, the air will struggle to pass air through your system, and that can throw things off — you may notice the real temperature in your home doesn’t match the thermostat display.
Dirty air filters can also cause your AC’s evaporator coil to freeze, preventing any cold air from circulating within your home. So, be sure to check the condition of your air filters and replace them when they’re dirty (typically every one to three months). That filter replacement will almost certainly make a difference when it comes to keeping cool when the mercury rises, plus it can help your equipment work more efficiently, and for longer.
Maintaining the Outdoor Unit
Your HVAC system has two coils: one indoor and one outdoor. Air passes through both coils, but only the indoor coil filters the air that you breathe. The condenser coil on your outdoor unit releases the heat that the evaporator coil collects from inside your home, and it doesn’t have a filter — you’ll need to keep it clean and clear yourself.
Clearing dirt and debris from your coil helps it transfer heat efficiently, and it’s an easy task: All you need to do is turn off the circuit breaker to the outdoor unit, then gently spray the outdoor unit with a hose to remove any potential blockage. When you’re done and the coil is dry, turn the circuit breaker back on and you’re good to go.
For any of your home appliances or systems to work, they need electricity. If your indoor or outdoor AC units lose power, you can’t count on cool air. So when the power goes out, check your circuit breaker and emergency shut-off switch, especially if a heat wave knocks out power in your region. Sometimes, simply restoring power to your AC system will fix the issue.
If you discover a tripped circuit breaker, only reset it once. If it keeps tripping, there’s a bigger issue that a trained technician will be able to diagnose.
Still Blowing Hot Air?
If you’ve checked your thermostat and cleaned the parts of your AC but it’s still blowing hot air, there may be a larger problem –– one that could be too tricky for a DIY solution.
Damaged AC parts often need to be repaired or replaced by a professional. Low refrigerant levels or problems with the condenser fan, compressor, or air ducts can be to blame for your warm air, and their complexity can call for the attention of an HVAC professional.
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