Check the circuit breakers for the furnace and the outdoor air conditioner. Check the switch on the side of the furnace, and the disconnect switch by the outdoor unit and make sure they are “on”.

Check your air filter; clean or replace as necessary.

Make sure the door to your furnace or air handler is installed correctly and securely. Newer units have a safety switch that shuts the unit “off” if the door isn’t securely in place for safety reasons.

 Check all registers and grilles to make sure they are clean, open, and not blocked by furniture.

Proper Air Flow: Without the right amount of air flow, the system can’t remove the heat from your home or business. The most common causes for inadequate airflow are a dirty filter, a dirty indoor coil, closed or restricted registers or grilles, or a dirty blower. Any of these can cause your system to lose capacity and may cause the unit to “freeze up”. Any signs of frost or ice on the piping by your furnace or fan coil unit are an indicator that you may have restricted airflow. If you see frost, turn the “cool” switch on your thermostat to “off”, turn the fan switch to “on” and let the fan run continuously to melt the ice build up on the coil (this may take several hours). Check all registers and grilles to be sure they aren’t closed or blocked, vacuum any unusual amount of dust build-up that may have accumulated on the return air grilles (the larger grilles that are usually mounted on the wall near the floor level), and replace or clean your filter. After 3 or 4 hours, the ice should be melted and you can try turning the cooling “on” again at the thermostat. If it freezes again, call for service as you probably have a more serious problem that needs professional attention. All of these items are addressed when we perform a Precision Tune-Up & Professional Cleaning on your system.

A Low Refrigerant Charge: A refrigeration system is a sealed system and contains a refrigerant, most commonly Refrigerant 22. The correct refrigerant charge is critical for providing proper capacity and ensuring reliable operation. A 7% under or overcharge can result in as much as a 25% loss in capacity, higher energy consumption, and reduced compressor life. A study performed by Louisianna State University found that over half of all the air conditioners they tested were not charged properly. This is why we spend so much time training and providing the right tools to pour technicians to do the job right. Over time, leaks may develop in a system due to loose connections, failed soldered or welded joints, leaky valves, or a unit that has been damaged. Even a small leak can cause reduced capacity, increased wear on the compressor, and can develop the same symptoms as inadequate airflow such as a freezing coil. Simply adding refrigerant may solve the immediate problem and restore capacity temporarily, but the refrigerant will continue to leak and likely get worse with time until the leak is repaired. The only long term solution is to isolate and locate the leak, repair it, and recharge the system. Balancing the refrigerant charge is one of the most important parts of the Precision Tune-Up & Professional Cleaning we perform when doing professional maintenance on your cooling system.

Condensor Capacity: The outdoor portion of your system is called the condensor. Over time, the coils can get dirty with dust, mud, leaves, pet hair, cotton from cottonwood trees, etc. When these coils become dirty, they can’t get rid of the heat as well and can cause the unit to overheat. When the unit overheats, it increases the energy consumption and operating temperatures in the compressor which can cause it to overheat further and lead to shortened compressor life and inadequate cooling (similar to running you car without enough antifreeze/coolant in the radiator). Some higher quality units have special safety devices to shut the system down before compressor damage occurs. Keeping these coils clean and free from debris, and keeping shrubbery and foliage trimmed around the unit, is important to keep it running cool. We use a special outdoor coil cleaner when we perform a Precision Tune-Up & Professional Cleaning which restores the coil capacity to as near as new condition as possible.

Evaporator Capacity: The indoor coil mounted on the furnace or in the fan coil unit is where the actual cooling of the indoor air takes place. If this coil gets dirty, it’s often difficult to clean and may even require that it be removed to properly clean it. When this coil gets dirty, air flow is restricted and the transfer of heat from the indoor air to the refrigerant is hampered. A dirty coil is difficult to detect, diagnose and repair. Since it’s the most difficult maintenance task to perform, it’s the most often overlooked by most simple air conditioner tune-ups; our Precision Tune-Up & Professional Cleaning includes cleaning the coil in-place. Keeping this coil as clean as possible is one of the main reasons for keeping your filter as clean as possible and also one of the reasons you should consider a high efficiency filter. Preventing one coil removal and cleaning job can more than pay for the cost of a high efficiency air filter.

Setting the Thermostat Too Low: This can cause the unit to freeze up since the air entering the coil is too cool to add enough heat to the coil. The coil temperature drops below 32 degrees and the water condensing on the coil will freeze. Although there are many variables with this condition, it rarely occurs on a system with proper airflow unless the thermostat is set below 70 degrees. A system with a weak blower, a poor duct system, or a duct system that has a lot of elbows or long duct runs can freeze even with 70-74 degree temperature setting.