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AC Won’t Turn On? 5 Things You Can Check Before Calling an HVAC Contractor


By Carrie Dixon, Blog Editor

Air conditioning has revolutionized modern life. We’re now able to stay cool and comfortable in our homes and businesses even during the height of summer. Of course, air conditioning systems can experience problems and when that happens, you’ll find that your comfort and even your safety are compromised if the mercury climbs enough. In addition to knowing some of the more common problems AC systems are prone to experiencing, you should also know a few steps to take to troubleshoot your air conditioning system before calling an HVAC contractor.

What to do before calling a local air conditioning contractor


1. Check the thermostat

It might sound trite, but the first thing to check is the simplest – the thermostat. Make sure that it’s set to on, and set to cool, not heat. Finally, make sure that the temperature control is set low enough that it will turn the air conditioner on. If you have a programmable thermostat, make sure that the time and date are set correctly, or the system might be operating in the power-saving mode reserved for times when you’re not at home. If everything looks normal, lower the thermostat’s temperature by five degrees and see if the unit comes on. If it does, then the thermostat was most likely set too high. If the unit does not turn on, you have another problem.


2. Check the breakers and fuses
The compressor on your air conditioner is run by electricity, which means that there is a potential for a problem with the breakers or fuses. The first place to look is inside your home’s breaker box. Use the schematic on the back side of the door to locate the breaker(s) for the AC system and flip them off, and then back on again. Do this even if the breaker looks like it is in the on position. If the breaker stays on, go back to the thermostat and turn the system on. If it works, you’re done. If not, go to the outside entrance panel and check the fuses. If they are blown, you’ll need to replace them before the AC system will work.


3. Check the AC condenser coils
The AC condenser is the exterior unit – the outside part of the air conditioning system. Don’t confuse this with the compressor, which is usually located inside the house. Because it is outside, the condenser can suffer from rust, corrosion, coating with debris and more. Check the system’s coils and if you notice rust or other corrosion, clean it. Make sure to turn the power to the system off before you do this. Once the coils are clean, turn the system back on and check to see if the AC is working.


4. Check the condenser fan
The condenser unit has a large fan that blows hot air into the atmosphere around the house. If the fan is not working, it puts a significant load on the AC system. Initially, the AC won’t cool properly, but it can overheat and trip the overheat protection switch. With the system on, turn down the thermostat to see if the fan on the condenser comes on. If it does not, you’ll need to call the professionals for help. On a related note, you should also check the blower on the indoor unit. If there’s no air coming from your vents, then the blower motor is not functioning – check to see if the exterior fan is blowing. If it is, but there is no air from the vents, then the problem is most likely with the blower motor. This could be something as simple as corroded electrical contacts, or it could be a complete blower motor failure.


5. Check the evaporator
The evaporator is part of the interior unit (inside the plenum). It’s located above the furnace, and sort of looks like a big metal wedge with pipes connected to it. Your evaporator may be protected by foil-wrapped insulation – this can be removed with care and set aside so you can get to the unit. Check the evaporator for signs of corrosion and buildup. If there is any, you’ll need to clean the evaporator coils, as well as the condensation tray located below, at the front of the unit. Once it is clean and the tray is empty of water (you may need to use a bleach/water mixture to do this), turn the power back on to the system and check to see if the air conditioner is working.


AC still not working? It may be time for professional help

While there are many things you can do to get your AC back in working condition on your own, there are quite a few problems that will require the help of a professional. If you’re unable to determine the cause of the problem, call a professional HVAC contractor for help.

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