How Does My Condenser Work?

On a residential split air conditioning system the condenser is the outdoor unit. It’s main job is to take the refrigerant as it comes outside from your home, as a gas, and condense it back into a liquid before sending it back inside. The liquid refrigerant then enters your evaporator coil to cool the air. The refrigerant inside your evaporator is a liquid, it absorbs the heat from the air in your home and boils off into a gas and is sent back outside to the condenser to be condensed back into a liquid again. This is your basic refrigeration cycle. 

On your basic system the condenser uses five main components to condense the refrigerant back into a liquid. These are the compressor, the condenser fan and condenser fan motor, the condenser coil, the contactor, and the run capacitor. 

  1. The compressor is the main component in the operation of the condenser. The compressor circulates the refrigerant through the entire system. It operates just like your heart, circulating blood throughout your body. It pulls the refrigerant outside from the evaporator coil and then forces it to move through the condenser coil to turn it back into a liquid. 
  1. The condenser coil (copper or aluminum tubing) is the next major component. The condenser coil is the tubing that runs all the way around your condensing unit. If you connected all the condenser coil piping end-to-end you would have anywhere from 150-300 feet of tubing. This is where the refrigerant as a gas has the heat removed so that it can be condensed back into a liquid. As air is pulled over the condenser coil the heat is pulled out of the refrigerant which cools it down back to a point where it turns back into a liquid. But what causes air to cross over the coils and remove heat…
  1. The condenser fan and condenser fan motor work to draw air across the condenser coil and remove the heat from the refrigerant cooling it down. If you ever hold your hand over the top of your condenser while it is running you’ll notice the air blowing out the top is much warmer than the ambient outside air. This is because the fan is drawing outside air across the coils, pulling the heat from the refrigerant, and then blowing the heated air out the top. This is one of the easiest ways to determine if your condenser is working, if the air blowing out the top is much warmer than the outside air. 
  1. The contactor is inside the control panel for the condenser. This is essentially the “on” switch for the condenser. When your thermostat tells your system that it needs air conditioning to turn on it sends 24-volts outside to energize the contactor which then switches on the high voltage to the compressor and the condenser fan motor. When the compressor and condenser fan motor turn on, the air conditioner begins to run full steam ahead. 
  1. The run capacitor is a small but very important component within the condenser. The run capacitor is what makes the motor in the compressor and the condenser fan motor operate. Without getting too technical your condenser motors run on two windings of single phase electricity, in order for the motors to run they need to have one of those windings “out of phase”. This is what the capacitor does. The high voltage power going to one of the windings passes through the capacitor first and has it’s phase shifted so it is out of phase with the other winding. This causes the magnetic motor to turn. Most condensers use a single capacitor for both the fan and the compressor, this is referred to as a dual run capacitor, this is because it is used for both motors. Sometimes you’ll have two capacitors, one for each motor, the compressor and the condenser fan motor, separately. 

To sum it up, when your thermostat calls for AC it energizes the contactor in your condenser. The contactor then sends high voltage to the compressor and the condenser fan motor. The high voltage for one of the windings in each motor passes through your run capacitor which enables both motors to begin to turn. Once the compressor is running it begins to move the refrigerant as a gas through the condenser coils where the condenser fan then draws outside air over the coils removing the heat and condensing the refrigerant back into a liquid. 

The compressor then sends the liquid back inside to the evaporator coil where it absorbs the heat from inside your home and starts the process all over again. 
That is, in a nutshell, what your condenser does, and how it works. For more information on the residential split system you have in your home click here, or watch the video on youtube here.