Split System Air Conditioner Not Working: Diagnosing the problem

It’s the peak of summer, and the heat couldn’t be any worse. You go to your thermostat and turn on the air conditioning expecting an icy summer treat to bring the temperature in your house down to a comfortable temperature. The blower kicks on, but there is no cool air coming out of the vents. Your mind goes into a panic with thoughts racing through your head… What should I do? Do I call a technician? How much is this going to cost me? Do I have to replace the whole outdoor unit? Don’t fret just yet. There are ways of diagnosing the system fairly easy without having to be a technician or calling one out, and odds are it probably is an easy and affordable fix.

Ok, so where do you start? That is a good question. First off we need to identify what’s happening at the unit. So with the thermostat set for cool and the fan inside running, you will need to go to the outdoor unit and make a visual and audible observation. These split condenser units are fairly simple with only a few parts in them. There would be a compressor, a contactor, a fan motor, a fan blade, and a capacitor.

Now let’s run down the items and determine what’s happening here.

Is the fan motor running and the blade spinning?

Is the compressor running?

Are both the compressor and fan motor not running at all?

If either of the motor or the compressor are working but the other item is not, then this is a pretty simple diagnosis. If the compressor is running but the fan motor is not, or vice versa, chances are it is just a capacitor issue. This is definitely the least expensive part to purchase if you are uncertain. To tell, simply take a stick and fish it down through the fan guard and try to spin the blade. If it kicks on, it is a bad capacitor for sure. If not, then your motor is bad and you would want to replace both the motor and the capacitor. If the motor is running and the compressor is not, then by changing the capacitor you will know if the compressor is bad by whether or not it fires up at that point. If after changing the capacitor the compressor does not kick on, then your compressor is bad. If neither of the compressor or motor is running, you can easily find the culprit to this problem. You will need to locate the access panel and remove it. If you follow the power lines coming from the house to the unit, the part that they are going to connect to is the contactor. On the top of the contactor there is a plunger style button, which when electricity is applied to the contactor coil, it becomes a magnet and pulls in that button bridging the live power across the contactor thereby giving power to the compressor and fan motor. If you turn the unit on and the button is not pulling in, this will tell you that either the contactor is bad, or the thermostat is not providing power to the contactor. To know for sure, take something non-conductive, like a stick, and push in the button. If you do this and the power to the compressor and fan kicks on, then we have identified the location of the problem. All there is left to do is verify that there is power coming to the contactor from the thermostat by using a volt meter on the thermostat wire. If there is power, the contactor is bad. If there is none, then there is a break somewhere between the thermostat and the wire. Tracing the wire to the break will tell you that the thermostat is either not sending a signal, or if the wire has a dead spot.

And that’s pretty much the jist of diagnosing your condenser problems. If you have determined what part you need, you can visit our website or call us and we would be happy to assist you in locating the part you need. Have a cool summer.