Troubleshooting Common AC Problems

Air Conditioner Coil is Frozen

Air conditioning filter is dirty – A dirty filter restricts airflow which can lead to a frozen coil. Turn the air conditioner off and change the filter. Turn the fan to “on” so the coil will thaw. After a few hours, turn the system back on. The problem could be solved.
The evaporator coil is dirty – If the air conditioner filter is not changed regularly, eventually the evaporator coil will become dirty. When a dirty coil restricts airflow, the coil can freeze. If the coil becomes dirty you will need an air conditioning company to clean it. Call 1st Class Heat and Air.
The system is low on refrigerant – If the air conditioner is running for extended periods it could be low on refrigerant. This can cause the coil to freeze. Turn the air conditioner off and the fan to “on”. After a few hours, the coil will thaw. Turn the unit back on. It could cool the house at first, but if it refreezes you should call 1st Class for service.

Check the breaker – Go to the electrical panel and see if the breaker has tripped. If it has tripped, flip it back on. All could be well. If it trips again, call 1st Class for service.
Check the thermostat – If it is a digital thermostat be sure the display screen is working. If the screen is not working try changing the batteries. If the display is working, be sure it is set properly. Make sure the system is set to “cool” and make sure the fan is set to “on”. Lower the temperature setting below room temperature.
Check the power switch – Many air conditioners have a power switch which can resemble a light switch, located near the furnace and evaporator coil. Make sure this has not been accidentally shut off.
Check the safety switch – Many air conditioners have a float safety switch which shuts it off when the condensation does not drain properly. Look at the condensate drain line or the drain pan and see if there is a safety switch shutting off the system.

Check the disconnect box – The disconnect box is also known as the external safety switch. When working on the condenser, the outside unit, the disconnect allows the power to be shut off. The disconnect is usually a box that is located on the house close to the outside unit.
Check the thermostat wire – Has anyone been weed eating or trimming around the outside condenser? Perhaps a dog or a new puppy has chewed the wires apart. If the thermostat wire is cut or damaged, repair it, or call 1st Class for service. Call for service if there are other problems.

There are many reasons the inside unit will not come on. It is best to call for an air conditioning service.
If the unit comes on but is not blowing air, look at the instructions involving a frozen coil.

We hope these air conditioner troubleshooting tips were helpful. For more information try our Air Conditioner Problems page.