Why Won’t My AC Turn On? A Portland Tech Explains

It’s frustrating when your AC won’t turn on when you need it.

We feel your frustration and, over the years, we’ve helped countless Portland homeowners fix their AC systems.

We’ve found that the four most common problems that keep your AC from turning on are:

• Your thermostat has a problem
• Your circuit breaker has tripped
• Your condensate drain line is clogged
• Your air filter is dirty

While we can’t properly diagnose the problem without coming to your home, we’ll discuss each of these common AC problems below and what you can do to fix them.

Rather have an HVAC professional come out to fix your AC ASAP? Contact Four Seasons for trustworthy, NATE-certified technicians.

Your thermostat is the “brains” of your AC operation. If your thermostat is malfunctioning or on the wrong settings, your AC won’t work properly.

To make sure your thermostat is not the issue, start by:

1. Checking to see if your thermostat’s screen is dead. If so, you might need to replace the batteries in your thermostat.
2. Making sure that your thermostat is set to COOL and not HEAT.

If your thermostat’s screen is alive and set to COOL, you may have a wiring issue. You’ll need to reach out to a professional for help.

Your AC may not be turning on because its circuit breaker has tripped.

Your circuit breaker’s purpose is to protect the electrical system in your home. It’s designed to trip and shut off power to certain circuits to prevent damage to the rest of your electrical system.

If there is a power surge or there are too many appliances in your home working at the same time, your AC’s circuit might try to use more electrical current than it can handle. Your circuit breaker can sense that the circuit is overloaded and will trip to kill power, which prevents your AC from turning on.

If you think a tripped circuit breaker is preventing your AC from turning on, you’ll want to go find your electrical panel (example below).

Next, you’ll want to:

1. Check if your circuit breaker has tripped. Your circuit breaker might have a red or orange color indicator to indicate tripping. If not, your switch will be in a neutral or OFF position.
2. Flip the AC switch so that it is OFF.
3. Then switch the AC switch ON.

If the breaker trips again immediately, do NOT reset it. Call a technician for help. You most likely have a short or grounded circuit, which a professional will need to resolve since trying to fix it yourself might result in serious electrical damage to your home.

A circuit breaker that trips again may also mean that you need to replace your circuit breaker since they wear out after continuous trips.

Your AC not only cools your home, but it also dehumidifies it. Your AC sucks in warm air from your home and blows that air over a cold evaporator coil, which chills the air. Condensation ends up forming on the cold evaporator coil when warm air blows over it. The condensation drips into a drain pan underneath the coil and then exits your home via the condensate drain line.

But, if the drain line gets clogged, water can end up backing up in the drain pan. If water is backing up in the drain pan, a drain float switch will activate, which will shut down your AC to prevent flooding.

If you believe that a clogged condensate drain line is your issue, you can unclog any blockages by:

1. Getting a wet/dry vacuum
2. Locating the condensate drain line outside your home (pictured below)
3. Sealing the wet/dry vacuum’s hose to the drain line
4. Turning the vacuum on for 3 minutes or so to suck out any debris

This solution should remove any clogs. However, if your clog is deep in the drain line or you’d like to prevent future clogs, contact an HVAC professional to regularly clean out your drain line during AC maintenance visits.

A dirty air filter prevents air from being sucked in by your AC. Reduced airflow is a problem because if not enough warm air is blowing over the coil, the coil can get so cold that it freezes.

When ice forms, a low-pressure switch in your AC will shut down the system to prevent it from being damaged.

If you believe that a dirty air filter is the issue, you can fix it fairly simply by:

1. Locating the return vent where air gets sucked into the AC.
2. Checking if you can see any light coming through the filter. If not and it looks like the picture below, it’s too dirty.
3. Replacing the filter if it’s dirty. You can buy air filters at home improvement stores.

To prevent future problems due to a dirty air filter, you’ll want to replace your air filter every 1-3 months.

If the above methods don’t work, you most likely have a bigger problem that requires an HVAC technician to fix, such as:

• Low refrigerant levels
• A dirty condenser
• Wiring problems
• Broken contactor or capacitor
• Malfunctioning motors
• Dysfunctional compressor

If so, the Four Seasons team is ready to help! We’ve repaired ACs for thousands of Oregon homeowners over the past four decades so we’re well-versed in all AC brands and models. Rest assured that we can get your AC up and running again.