AC Won't Turn On

An Iowa Homeowner’s Troubleshooting Guide

There’s nothing like the feeling when you finally decide to turn on the AC, you flip the switch on the thermostat and… nothing. Aspen Aire Heating & Cooling is a trusted HVAC company in the Des Moines area and we often get calls about air conditioners not working. If your AC won’t turn on, here are some common causes, possible solutions, and when to call an AC repair technician.

Troubleshooting a Home Air Conditioner Not Working

These are some common reasons your AC system won’t turn on, most of which you can fix yourself.

Thermostat Settings

Check your thermostat and make sure it’s set to “cool” and the set temperature is lower than the actual room temperature in your home. If the thermostat screen is blank, try changing the batteries. And if you have a smart thermostat, sometimes a simple restart can help.


This is one of the most common issues and the simplest to fix when an air conditioner won’t turn on. If your thermostat is set correctly but the AC unit doesn’t kick on, make sure your air conditioner has power. Here’s what to check:

Check the Circuit Breaker

Check the circuit breaker to see if it’s tripped. You might find the electrical panel in the garage, basement or spare bedroom. Newer breaker panels should have a circuit breaker labeled something like “AC” or “HVAC”. Make sure it’s in the “on” position. However, if you turn the breaker on and it immediately trips, there could be a bigger issue. Call an HVAC technician for service and don’t reset the breaker again.

Check the Switch at the Blower

There should be something that looks like a light switch next to your blower or furnace, which will be in the basement or utility closet. If you recently moved into your home, this switch may have been turned off by the landlord or previous tenants, so make sure the blower switch is on.

Check the Outdoor Power

Finally, check the disconnect switch for the outdoor AC unit to make sure it’s on. If you’ve had your air conditioner serviced, this switch could have been left in the off position by mistake.

Other Common Culprits When Your AC Won’t Turn On

These causes of an air conditioner that won’t turn on are more complex and will require a professional to troubleshoot and fix them.

Clogged Air Filter

Dirty air filters can reduce the airflow through your home’s central air system. This makes your air conditioner work harder and, if left unchecked, your air conditioner will shut down to prevent overheating the system.

Fortunately, replacing the air filter is a simple task. Simply look for a little door or opening next to or below the blower, usually toward the bottom of the HVAC unit. The filter should slide out so you can check the size and purchase a replacement. Then, simply, throw away the old filter and slide in the new one.

Frozen Evaporator Coils

The evaporator is the part of your central air conditioning system that’s located inside the house. It has coils inside that the refrigerant flows through. These evaporator coils can freeze if they’re dirty, like from a clogged air filter, or there’s not enough refrigerant in them. If you see ice on your air conditioner’s condenser unit, turn off the air conditioner to let the evaporator coils thaw.

After the ice has melted from the frozen evaporator coils, you could try changing the air filter, but it’s best to have an HVAC technician clean your AC and test your cooling system for a refrigerant leak.

Water in the Drain Pan

Your home’s central air conditioner is like a giant dehumidifier that removes moisture from the air as it cools your home. This moisture collects in a drain pan inside your HVAC system, which has a pipe connected to it called the condensate drain line that transfers the water out of your home. If the drain line gets clogged, the condensate drain pan will get too full and a sensor will shut off the HVAC system. This is a safety feature to prevent flooding, but it can be frustrating for homeowners who don’t realize there’s an issue.

You may be able to use a shop vac to clear water out of the condensate drain and get the air conditioner working again. However, this will likely be a temporary fix and you should call a qualified HVAC company to inspect the system and unclog the condensate drain line if needed.

When to Call an HVAC Professional

  • If there’s a burning smell
  • Hearing strange noises from the indoor or outdoor unit
  • Outdoor AC unit tries to run but fan isn’t working
  • Fan inside at the blower isn’t working
  • If these basic troubleshooting steps don’t work

No one wants to call an AC repair company, but you’ll get the benefit of a correct diagnosis of the issue, a safe repair, and you can avoid further damage. Aspen Aire Heating & Cooling provides professional air conditioner repair in Des Moines, Ankeny, and the surrounding Iowa communities.

How to Prevent AC Breakdowns

  • Schedule annual AC tune-ups before summer
  • Change furnace filters regularly
  • Keep the outdoor AC unit clear of debris

In the Des Moines area, Aspen Aire Heating & Cooling offers a membership program to help you save money on both AC tune-ups and repairs.

Request Expert AC Repair in Des Moines

If your air conditioner won’t turn on, start with these simple central air troubleshooting steps to see if there’s a solution you can handle yourself. If that doesn’t fix the issue, contact a local HVAC company to fix your air conditioning system so it will cool your home again. In central Iowa, contact Aspen Aire Heating & Cooling at 515-257-8370.