It is a big deal when the air conditioning goes out on a hot summer day, but there is no need to wait for help to come to you.  Many air conditioning malfunctions are not difficult to identify and repair.  The following test procedure will help you identify if the problem with your outdoor unit is the fan motor, the capacitor, or the contactor.Troubleshooting the “outdoor air conditioner unit not running” starts with some easy commonsense steps:Section A; you can hear the a/c compressor running and the fan motor is not turning.Because the compressor is running you know there is 220 volts power to the outdoor unit and you know the contactor is doing its job of delivering that 220 volts to the compressor and to the motor.  The malfunction will be a bad capacitor and/or a bad motor. Capacitors can be tested with multi-meters that have the ability to read microfarads or you can take your capacitor (and your motor) to your nearest U-FIX-IT store for a free bench test.  If the capacitor tests good then your motor is bad.

Caution – Capacitors can store an electric charge (like a battery).  what to do if your ac unit freezes upThe shock hazard is non-lethal, but it is no fun.   ac window unit energy usageCheck the 220 volt power is off and discharge the capacitor by shorting between capacitor terminals (with insulated screwdriver) before removing the wires from the terminals.2nd hand air conditioning unitsyou cannot hear the a/c compressor running and the fan motor is not turning.  Your next troubleshooting step will be checking the 220 volt power because it is highly unlikely both the compressor and the fan motor would fail at the same time.  Failure of the contactor (see picture above) most often produces this symptom.  You can prove the contactor is the problem by using a multi-meter or you can take your contactor to your nearest U-FIX-IT store for a free bench test.

Testing the contactor on air conditioner outdoor unitCaution: use care when measuring live voltages not to touch bare connections or short them to the cabinet or to other terminals with the meter probes.Part Request Part Number or Description*Email* More From Jim PlummerJim is an ex-Air Force pilot and a business school graduate of University of Texas at Austin. He has been in the appliance parts business since 1975.Before you make that call, try this basic air conditioner troubleshooting guide. This guide will help you to diagnose problems with your typical ducted split type air conditioner. A typical repairman will cost you about one hundred dollars per hour. With a few household tools and a little bit of knowledge, you can do it yourself and save that money. (You provide the tools and we will help with the knowledge part.)You should ensure that the routine maintenance has been performed on the unit. If the air filter has not been changed in the past month, check to see if it is dirty.

**NOTE** ONLY YOU CAN ASSESS YOUR ABILITY TO PERFORM THIS TASK. THIS IS A GUIDE AND CANNOT PROVIDE ALL OF THE DETAILS FOR EVERY SITUATION. Begin your air conditioner troubleshooting at the thermostat by ensuring that the thermostat is on cool and that it is set lower than actual room temperature. This is to ensure that there really is a problem. It may seem silly but that is the first thing a repairman will check and you will normally still be charged a service call even if that is the only problem. If there is not, then, check to see if the fan on the outside unit is running. If the fan on the outside unit is not running either, check to make sure that the breakers for the furnace/air handler and the air conditioner are on. If the breaker is not tripped, then the problem may be your thermostat, the furnace/air handler control board, or the wires between the furnace/air handler and the thermostat. If your unit has a condensate pump, check to make sure the reservoir is not full.

If the reservoir is full, a limit switch will normally stop the air conditioner from running. You will need to repair or replace the pump.If the breaker is tripped, you can reset it by shutting it off and then turning it back on. If it trips again, then check the wiring in the furnace/air handler for signs of damage and repair as necessary.If the blower is running but the fan on the outside unit is not, then continue your air conditioner troubleshooting at the outside unit. If the blower isn't running but the fan outside is, the problem could be the blower motor, it's run capacitor, or the furnace/air handler control board.If the fan motor is not running, then shut the power off to the unit. Then check all wire connections for signs of damage such as burning and repair as necessary. You should also check the wire connections in the compressor terminal box and repair if necessary. You can use our capacitor testing guide to check the unit's capacitors and replace as necessary.

Continue your air conditioner troubleshooting by turning the power back on to the unit and observe whether the contactor closes or not. If the unit does not start, look for a reset button. Some units have a high pressure cutout switch that can be reset. Then, use a voltmeter to check to see if you have power to the unit and 24 vac to the contactor's coil. If you do not have power to the unit, you should check the wiring between the electric panel and the unit. If you do not have 24 volts to the contactor's coil, check the thermostat and the low voltage wires from the furnace/air handler to the condensing unit. If you have power to the unit and the coil on the contactor but the unit does not start, the unit's contactor may be bad.If the compressor starts but the fan does not, the condenser fan motor could be the problem.If the condenser fan starts but the compressor does not, the unit may be low on refrigerant, the compressor might be too hot, or the compressor might be bad. If the blower on the furnace is running, check to see if you see any frost or ice around the units.

You might also notice water around the furnace. Is there ice on the copper lines going outside? If yes, then shut the outside unit off for a couple of hours but let the blower on the furnace run. This will allow the ice to melt. After two hours, you can continue your air conditioner troubleshooting. Turn the ac back on and let it run for about five minutes. Now feel the larger copper line at the outdoor unit. This should be cold and have condensation on it. If it is not cold or if frost is forming on the line, it is probably a freon problem. You will need to call a repairman because of federal refrigerant usage regulations.If there is no ice or frost, then continue troubleshooting at the outside unit. If the condenser fan and the compressor both run but the cooling effect is not adequate, you should check the temperature drop of the system. To measure the temperature drop, measure the air temperature leaving the air handler and subtract it from the temperature of the air entering the air handler.