What to Check When Air Conditioner Isn’t Cooling

What to Check When Air Conditioner Isn’t Cooling – One of the biggest frustrations at the start of summer is turning on your air conditioner, only to find the air output isn’t cold. Here are a few common, simple things to check before you call a professional.

What to Check When Air Conditioner Isn’t Cooling

ThermostatWhat to Check When Air Conditioner Isn't Cooling

Many thermostats need to be switched from “heat” to “cool” in order to run the air conditioner. If this has not been reset yet, this is the first place to start.

Moving the thermostat from heating to cooling will allow the system to shift. Adjust the thermostat to at least five degrees below the room’s current temperature, then give it a few minutes to switch over and start blowing cool air.

If the thermostat is set to “auto”, it will cycle the room’s air for periods of time. To test the air conditioner, switch the system from “auto” to “on” to make sure AC is working correctly.


Make sure all vents are open and not clogged with dirt or debris. Also make sure there is not furniture blocking the vents. Having a couch, chair, rug or other piece of furniture over a vent can prevent cool air from entering the room.

Air filter

Air filters are easy to replace and not too costly, however, many homeowners overlook the importance of replacing them regularly. Air filters should be replaced every three to four months. If the air filter is full, it will restrict air flow through the air conditioning unit limiting the cool air output.

To check your central air furnace filter, open the furnace door and look for the thin tray. It usually sits vertically or horizontally, depending on the direction of the air flow through the unit. If there is not an air filter in the furnace unit, it may also be in the return grill at another location in the home.


Check the switches on the thermostat and on the unit itself. If these are set to “on”, check the circuit breaker for power, as well. If a switch has been flipped or if the circuit breaker is tripped, it may indicate a bigger problem with the air conditioning unit. These switches are designed to cut power for safety if there is a surge or other electrical problem.

Outdoor condenser unit

Outdoor condensers are usually set up somewhere around the house, surrounded by landscaping or grass. Many times, the landscape grows up around the condenser or drops debris such as leaves, sticks and pine needles during the winter and spring.

This debris can block the airflow to the condenser causing slow airflow, impacting the condenser’s ability to cool. If there is landscape within a couple feet of the condenser, it needs to be cut back at least a foot or two to allow smooth airflow.

In addition to a visual inspection, listen to see if there is any clicking, surging or other abnormal noise coming from the unit.

Condenser coil

To get a good view of the condenser coil, you’ll have to look up into the side vents until you can see the aluminum coil. A buildup of dust, or other debris on the outside of the unit or on the condenser coil needs to be cleaned.

The best way to clean the condenser coil is from the inside out, in order to avoid damage to the unit.

Call a professional

If each of these items checks out and you are still feeling a less than optimal cooling from your air conditioner, call us at Pilchuck Heating to set up a professional inspection.

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