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Turning on the air conditioner.

As the summer heats up and you turn on your air conditioner for the first time, you may eagerly await a rush of cold air coming from your vents. But what if the AC doesn’t turn on, or it keeps shutting itself off? You’re already on the verge of being too hot, so you don’t have much time to set things right until you become uncomfortable. Here’s how to troubleshoot an AC that won’t kick on before you call an HVAC technician for help.

Check the Thermostat

If you start feeling a bit warm and wonder why the air conditioner hasn’t turned on yet, double-check the thermostat. A family member may have altered the settings without your knowledge, or you may have forgotten to switch the thermostat from “heating” to “cooling” mode.

After making sure the mode is correct, set the temperature 5 degrees below the current indoor reading. If the AC still doesn’t turn on, or you discover that the thermostat screen is blank, change the batteries. You can also try turning off the system, waiting five minutes, and turning it on again.

Look for a Tripped Circuit Breaker

A power surge can cause the air conditioner to trip a circuit breaker, especially if it shares a circuit with another appliance. Check the main breaker box to see if one of the breakers doesn’t line up with the rest. If so, flip it all the way off and then back on again. Fixing this problem once means it was a fluke, but if it keeps happening, you should hire an electrician to take a look.

Check for a Blown Fuse

Another possibility is that the fuse in the outdoor shutoff box has blown. Check near the exterior AC unit for this metal box mounted to the house, and replace any blown fuse you find inside.

Check the Emergency Shutoff Switch

While you’re outside, check the shutoff box to see if the power has been turned off. If someone recently worked on the air conditioner, they may have accidentally left the switch in the “off” position. Restore power, and the AC unit should turn on.

Press the Reset Button

If everything appears to be fine inside the shutoff box, inspect the outdoor unit itself. Some systems have a reset switch you can press that may get it running again.

Check the Indoor Unit’s Power Switch

There’s another switch located near the indoor air handler. This looks similar to a light switch and controls power to the interior portion of your air conditioner. Make sure it’s set to the “on” position.

Ensure the Condensate Drain Line isn’t Clogged

While you’re checking around the indoor air handler, look down at the condensate drain pan. If it’s full of water, this could mean the drain line is clogged with algae or other debris. A safety switch has sensed the rising water level and shut off the air conditioner to prevent water damage. This is most likely to occur if you have been running your air conditioner overtime during a heat wave.

You’ll need to unclog the condensate drain line and empty the pan to get the AC running again. Then, to prevent a recurrence, ask your HVAC technician to treat the line with algaecide during your next air conditioning tune-up.

Change the Air Filter

Another common air conditioner problem is when the unit turns on, but it only runs for a short time before shutting back off. Known as short-cycling, this issue prevents the AC from cooling and dehumidifying your home properly.

A dirty air filter is a common cause of short-cycling. Inspect the filter to see if it has become clogged with dust, hair, and other debris. This restricts airflow, triggering the air conditioner to shut off before it overheats. If the filter is clogged, change it now. Then, remember to replace it every three months to prevent this problem in the future.

Look for Icy Buildup on the Evaporator Coil

The indoor air conditioning coil transports cold refrigerant. When hot indoor air blows over it, the refrigerant absorbs the heat, leaving cool air to circulate back into your home. The coil also collects condensation as it cools the humid air, which drips into the condensate drain pan and flows away.

If airflow through the system is weak, the evaporator coil is dirty, or the refrigerant charge is low, condensation on the coil may freeze. When this happens, the air conditioner operates, but the air blowing from your vents feels lukewarm at best.

Check for icy buildup on the evaporator coil to see if this is the reason for your air conditioning woes. The AC won’t work properly again until the ice thaws, which can take up to 24 hours. Changing the filter may resolve the issue, but a dirty coil or low refrigerant charge requires a technician’s help.

Call Allen Service If Your AC Won’t Turn On

If these troubleshooting tips don’t get your air conditioner working again, a more serious underlying problem could be to blame. There may be a refrigerant leak, faulty motor, bad wiring, broken thermostat, or another issue. In this case, you need professional AC repair from a knowledgeable HVAC contractor.

Allen Service is the right company for the job. A trusted name in heating and cooling repair for nearly six decades, Allen Service delivers quality work at affordable prices. Call us today at 970-484-4841 or contact us online to request air conditioning repair in Fort Collins. A fully licensed, certified, and insured technician will arrive promptly to diagnose and fix the problem.