Why Won't My Central Air Get Cold?

If your central air isn't cold, first make sure it's getting power.

There is little point in having the luxury of air conditioning if the air conditioner will not cool the home. If the air will not get cold, there could be one of several problems with the central air conditioning unit Start by checking the simple things you can quickly fix on your own before calling a repair technician. Keep working your way down the list of possibilities until you hopefully land on the solution.

Thermostat Setting

Start by checking the basic settings of your thermostat. In some cases a switch may have been bumped accidentally while adjusting the system or a shoulder just brushed the dial, turning it off.

See if the temperature is set to a level that will allow the home to get cold. If the room temperature is already lower than the setting, the air conditioner will not cool the home. Turn it down to a lower temperature to test it out. Also make sure the switch is set to "cool" instead of "heat," "fan" or "off." The wrong setting could make it blow air that is hot or room temperature or not at all.

Registers Open

If you can hear your system running normally but don't think the house is cooling correctly, it could be something as simple as closed registers. The registers are the vents where the air from your central heat and air system enter the house. These are built with shut-off switches or adjusters to help you regulate the direction and amount of air coming in from the system.

If you have key registers in the closed position, the rooms will not cool properly. Check these to make sure the vents are completely open.

Filters

Over a relatively short period of time, an air conditioning system will suck enough dust and debris into the intake to make the filter quite dirty. If the filter becomes so dirty that is clogs the way for circulating air to get back into the system, it will prevent proper cooling. Change your filters regularly to avoid this efficiency problem. Extremely dirty filters could even cause overheating and severely damage the unit.

Fans

Your central air conditioning unit generally has two fans. Find out if both are running. There will be a fan on the outside unit and one inside in most systems. If the outside compressor fan is not running, it could cause an overheating problem that will cause inadequate cooling.

If the indoor air handler fan isn't running, it will also cause a lack of cool air. Check the power switches on both units and the associated breakers to make sure the system is being powered properly, notes the Inspectapedia website.

Refrigerant

If your air conditioner is not cooling properly, there is a chance you have a refrigerant leak or it has all been used up by the system. This will require a Freon recharge that will likely have to be done by a repairman. Call an HVAC technician to come out and test the refrigerant level and check for leaks. He can recharge the system, fix any leaks and have the air cold again in no time.

References

• Inspectapedia: How to Diagnose & Repair Loss of Air Conditioner Cooling Capacity or an Air Conditioner that is Not Working
• Home Improvements Depot: Central Air Conditioner Not Working? Try These Simple Troubleshooting Steps
• Central Connecticut Home Inspection: Facts & Tips on Central Air Conditioning Systems