Central air conditioners are like any other appliance in that the unit requires occasional maintenance and repair to work efficiently. If the vents in your house have stopped putting out cold air regardless of your thermostat settings, there's a problem somewhere in your unit.

A few different problems can cause the cooling to stop. You can diagnose the problem through a bit of cleaning and testing or skip ahead to calling an air conditioning repair technician for assistance.

Here are three potential fixes for a central air conditioner that isn't cooling the air.

Condenser Coils

The cooling process begins in the condensing unit outside your home. Inside the condensing case, there is a compressor that pushes refrigerant gas into condenser coils, which turns the gas into a liquid. This liquid is then able to pass through pipes into your home to power the cooling process in the air handler.

If the condenser coils are dirty or damaged, the coils aren't able to convert enough of the refrigerant to pass along to the evaporator coils inside the house. How do you know if it is the condenser coils causing the problem?

Troubleshoot by cleaning the coils and then testing the system again. To clean the coils, turn off all electricity going to the condensing unit. Remove the unit's cover and locate the coils that line the interior wall. Point the end of a spray nozzle hose through the coils form the inside – meaning, you want to point the hose back out towards where you're standing.

Rinse the coils until they appear clean. Put the unit back together and turn the power back on. Lower the thermostat inside the house and wait an hour or two to see if the air becomes cool. If it doesn't, you can continue troubleshooting and then call a professional.

Evaporator Coils

The evaporator coils inside the air handler transform the gas refrigerant back into a liquid. This phase change cools the coils, which then cool the room's air that's sucked in by the return vent.

If the evaporator coils become dirty or damaged, the coils won't cool enough to lower the temperature of the air sucked into the air handler. So when the blower fan goes to push that air back out into the room, the air is essentially the same temperature it was when it went into the handler.

You can clean evaporator coils using a store-bought foaming cleaner that doesn't require rinsing. Follow the package directions on the cleaner. As always, make sure the electricity is turned off to the unit before you clean. And call a professional if the task seems above your knowledge level.

Refrigerant

Over time, the refrigerant in the system can degrade and become less efficient at moving through and cooling the evaporator coils. If the condenser and evaporator coils both seem fine, it's likely a refrigerant issue.

You always want to leave refrigerant issues in the hands of a professional. In many areas, it's illegal for a novice to own and operate the type of refrigerant used in an air conditioner. So it's not the sort of fluid you want to improvise with if you don't know what you're doing.

Talk to experts like Daryl's Heating & Air Inc for more information.