4 Reasons Your Brand-New Air Conditioner Isn't Cooling

Just because your new air conditioner was recently purchased and installed doesn't make it immune to immediate problems. One of the main concerns about any central air conditioner is its inability to cool. If your brand new air conditioner isn't cooling, it's likely caused by a setting error, incorrect installation, blocked or frozen condenser, or issues with the registers or ducts. If you can't identify the issue from a few quick checks, you need to contact the HVAC crew that installed the system and have them check it out.

Here's why your new air conditioner isn't cooling — and what to do about it.

If you call out an HVAC repair technician, the first thing the tech will check for is user error. Check this out yourself by looking at the settings on the controls. Make sure they're all in the correct position. Set the unit to "cool" instead of "heat" or "off." Make sure the thermostat is set to a temperature that is lower than the ambient temperature in the house.

If these settings are wrong, the air conditioner will blow warm air or won't blow at all. This is a simple fix and is a common error by those who aren't used to dealing with an air conditioner.

Where the installer positions the thermostat on a central air conditioning unit is more important than you might think. The position of the thermostat may prevent your system from maintaining the desired temperature in your home. It could be in a place where an air vent blows directly on it, cooling it quickly below the desired temperature setting. This causes the thermostat to send a signal to shut off the system, resulting in your home not getting cool enough.

The opposite is true of thermostats located in the direct sunlight during part of the day. The radiant heat makes the thermostat hotter than the rest of the house and may force it to turn on the system, which will cool continuously and make the house too cold. The thermostat should be in a spot away from vents and out of the sunlight. You might need to move the thermostat if it's in a bad location.

An air conditioner will stop cooling properly when its condenser coil freezes up. The flow of air is restricted during these times, making for inefficient cooling. The reason condenser coils freeze may be because of low refrigerant charge, which may indicate a leak. Your air conditioner will not "run out" of refrigerant; however, leakage requires the attention of a licensed professional.

Dirty evaporator coils may be the culprit, putting extra strain on your air conditioning system and threatening to cause a freeze-up. If you don't clean the condenser coils periodically, they may well freeze.

Debris or tall grass hindering the airflow around the unit intakes could also lead to excessive frost and freezing, which result in the same lack of cooling. Use a string trimmer periodically to keep vegetation away from your new air conditioner. If you see that your condenser coil is frozen, clear away any debris from around the outside unit, and get the installer back out to check for leaks and refrigerant level.

Once the air conditioner makes cool air, it must deliver it throughout the home using a system of ducts and out through registers or vents. If the ducts aren't properly installed and the cool air is leaking from them before entering the home, it can drastically affect performance to the point where the A/C isn't cooling.

Also, if the HVAC registers are in a closed position, the air cannot get into the house. Check your ducts for air leaks and make sure your registers are all open completely to maximize cooling.