Central air conditioning system not cooling properly or working at all? There are some simple steps you can take before seeking experienced advice.

STEP 1: Determine what part of the system is working. There is an indoor unit (evaporator) and an outdoor unit (condenser). The indoor evaporator may have its own unit (air handler) or used with a furnace's blower (fan). At the thermostat turn the "COOL" switch to "OFF" and the "FAN" switch to "AUTO". The system should shut down. Some systems have a time delay, but should shut off in a few minutes. If the system does not shut off in 10 minutes, make sure you are controlling the right thermostat to the system. 

STEP 2: Find the electrical breakers to the units and switch both the outdoor and indoor units to the "OFF" position. The indoor unit breaker may be to an air handler or a furnace. The outdoor unit will be on a two breaker (double-pole) switch. The indoor unit may be on either a single or double switch. Both systems should be completely shut down now. If a unit is still running, you are not switching off the correct breaker. You may have to switch off breakers until you find the right one. Once you find the right one, label it.

STEP 3: Go to the indoor unit. Is there any water coming from the unit onto the floor or into a drain pan? Is there any ice formed on the unit, pipes or duct work? Remove the filter and check to see if it is dirty. Is it wet? If ice or water leakage is visible, you will need to wait until the ice melts before replacing a new filter and continuing to the next step. DO NOT try to pick off the ice! You can cause a refrigerant leak! You can place towels around the unit to catch the water. There may be a lot of water before it's all melted! Once the ice has melted and the water is dried, you can install a new, clean filter. 

STEP 4: Turn on the electrical breaker for the indoor unit ONLY.  At the thermostat, turn ONLY the fan switch to "ON". Only the indoor unit should come on. If the indoor unit does not come on with both the electrical breaker and the thermostat fan set to "ON", contact us below. If the indoor unit comes on, go to a vent that you know has air flow and feel if there is air coming out of it. If little or no air is coming from the vent, the ice may not be completely melted, the indoor coil (evaporator) is dirty, or the blower (fan) is not working properly. Contact us below. If there is normal air flow coming from the vent, proceed to the next step. 

STEP 5: Turn on the electrical breaker to the outdoor (condensing) unit. At the thermostat, turn the switch from "OFF" to "COOL" and make sure the temperature setting is 10 or more degrees below the room temperature. Does the outdoor unit come on? If so, wait about 10 minutes and check again. Is it still on? Check the vent mentioned in step 4. Is the air getting cooler? If the outdoor unit shuts off, the air doesn't seem to be getting cooler, or the room temperature doesn't start to come down; there are other major issues that need to be addressed. HVAC technicians are standing by to answer your air conditioning questions! <ASK AC QUESTIONS HERE>

HVACR Technicians are contributing writers for this blog and for HVACASAP.com.