Air Conditioner Problems

air conditioner problemsLocate the Source of the Problem

If your air conditioner is not working you should locate the source of the problem. When you turn on the air conditioner, what happens: A) Nothing. B) Outside unit does not come on. C) Inside unit does not come on. D) Both inside and outside units come on but the air is hot.

A) Nothing Happens When the Air Conditioner is Turned On

If you turn on your air conditioner and nothing happens, check these things. They can help you identify many air conditioner problems.

Circuit Breaker 

Check the circuit breaker. If it has tripped, flip it back on. If your air conditioner comes back on, all could be well. A power surge could have caused the breaker to trip. If the breaker trips again you should call for service. Note that older homes may have a fuse box.


Check the thermostat to be sure it is set properly, so that the  air conditioner will come on. The thermostat should be set to COOL instead of HEAT or OFF. With the thermostat set in the COOL position, the temperature setting needs to be lower than the room temperature. That is, if the room temperature is 71 degrees and the thermostat is set to 72 degrees, the AC system will not come on. Additionally if you have a programmable thermostat, be sure that the program settings do not conflict with the AC’s operation.

Power Switch

Has anyone been in your attic recently. There is a power switch connected to many air conditioning systems that looks like a light switch. If someone has been in the attic, there is a chance they could have flipped the power to your unit off. If someone has been in your attic, check the power switch. It looks like a light switch and will be located near your unit. If it is turned off, just turn it back on. This is a frequent problem in the winter when many people are in the attic getting their Christmas lights and returning them to the attic. Of course when they turn off the power switch, it is in the winter and they have no heat.

Safety Switch

Most air conditioning systems have a float safety switch that can shut off the system. If you have been experiencing a plumbing issue it can also affect your air conditioning system. Air conditioners are designed to remove moisture from the air in the form of condensation. This water is routed into the plumbing system and if the plumbing backs up the float safety switch can shut down the air conditioner. You could also experience an intermittent problem. Water could back up in the plumbing and the float safety switch could turn off the system. With the system off, the water could gradually drain if it is a partial clog. This would allow the air conditioner to turn on again until the water again backed up and the safety switch shut it off. If you have a drain problem, get the drain cleared. If you cannot do it yourself, your air conditioning service expert can help. However, if your main drain is clogged, you should call a plumber.

Door Switch

If someone has been looking at the inside unit and has taken the door off the gas furnace or electric handler, there is a chance that the door is not installed properly. There is a switch in the door that will not allow the unit to come on if the door is not closed properly. If no one has removed the door, this is unlikely to be the source of you air conditioner problem.

B) Outside Unit Is Not Coming On

If your air conditioner is blowing warm air your should check to see if the outside unit is coming on. If the outside unit is not coming on you should check these things.

Disconnect Box

This is also known as an external safety switch. It allows the power to the outside unit (condenser) to be turned off, so it can be worked on. Be sure that the power is turned on to the unit. This is usually a box that is located on the wall of the house near the air conditioner.

Thermostat Wire

Do you have dogs or maybe a puppy. Has anyone been operating a weed eater around the air conditioning condenser. Check the small low voltage wire that is connected to the AC condensing unit to be sure it is not cut. If you see that the wire is cut, repair it yourself, if you can, or call for an AC service technician.

C) Inside Unit is Not Coming On

If the inside unit does not come on and the outside unit does, the problem is likely related to the blower motor. Be it a circuit board, capacitor or motor itself, most people will need to call for service.

D) Both Outside and Inside Units Come On, Air Conditioner Is Not Cooling

If your turn on your air conditioner and it is not cooling but both the outside and inside units are running, the following needs checked:

Air Conditioning Filter

Has it been a while since you changed your air conditioning filter? If so, did you know that a clogged filter could be the source of your problem. If you have an extremely clogged and dirty AC filter the system will not be able to move enough cool air to satisfy the thermostat. It will run and run causing the coil to freeze which further restricts air flow. If your filter is dirty, change it. You may not be able to get the system to work right away because there may be ice on the evaporator coil. Turn the fan from AUTO to ON as it will help the evaporator coil to thaw. After the system thaws, turn it back on. If the system refreezes, you have other issues. One of those issues could be a dirty evaporator coil which is caused by a not changing your filters often enough. If you have pets or like to leave your fan in the ON position to circulate air your AC filter will need changed more often. Be sure to use the pleated filter and not the cheap fiberglass filters. The pleated filters work much better than the fiberglass ones.

Air Conditioning Condenser

Check the outside air conditioning condenser to see if there is any ice on it. If there is ice, be sure that you have checked your air conditioning filter as stated above. If you change your filters regularly and use a decent filters, you likely have a refrigerant problem. If you have a refrigerant problem you must call a licensed AC contractor for service.

Important    –  If your air conditioner is frozen, turn it off. The ice needs to melt before a technician can work on it. Go ahead and call for service but explain that the unit is frozen and schedule service 3 or 4 hours after you turn the system off. Turn the system to OFF and the fan to ON to help melt the ice.  

We hope that these air conditioning tips can help you with your air conditioner problems. If you need an air conditioning technician  call 1st Class Heat and Air. We are a company that you can depend on. We provide service for air conditioning problems in Addison, Allen, Balch Springs, Bartonville, Carrollton, Coppell, Copper Canyon, The Colony, Corinth, Dallas, Denton, Double Oak, Fairview, Farmers Branch, Flower Mound, Forney, Frisco, Garland, Grapevine, Heath, Hackberry, Hickory Creek, Highland Park, Highland Village, Irving, Lake Dallas, Lakewood Village, Lavon, Lewisville, Little Elm, Lucas, McKinney, Mesquite, Murphy, Oak Point, Plano, Princeton, Prosper, Richardson, Rockwall, Rowlett, Royse City, Sachse, Shady Shores, Southlake, Sunnyvale, University Park, and Wylie.  Do you need AC repair Plano? Call us today.


how to diagnose air conditioner problems infographic 

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This air conditioner problem is an example of a rusting evaporator coil. This can cause your coil to develop refrigerant leaks. Once a rusted coil develops a refrigerant leak the likely outcome is to replace the coil. This is a common air conditioner problem?

ac coil problem

This air conditioner problem is an example of a dirty air conditioning evaporator coil. This is what happens when your air conditioning filter is not changed regularly.
air conditioning problem
Here is a close up of the above evaporator coil. The main cause of this air conditioner problem is failure to change the air conditioning filter. You can easily see that air will have a problem passing through this coil. There is dirt, pet hair and what appears to be mold on the coil. All the air that is circulated through the house passes through this coil.AC filter problem

This customer has a sense of humor. Her problem was a simple fix.