A central air conditioner relies on two different sets of coils to keep the chemical refrigerant moving through the system to fuel cooling. The first set of coils resides in the outdoor condensing unit and are called condensing coils. What purpose do these coils serve, why is their proper operation vital to the air conditioner, and what malfunctions in the coils can thwart your system?
Condensing Coil Function and Importance
The condensing coils are attached to an interior wall of the condensing unit and positioned adjacent to the compressor, which starts the cooling process off after the thermostat signals the unit to turn on. The compressor compresses a gas refrigerant out into the condensing coils.
The refrigerant eventually needs to travel inside to the air handler within your furnace to finish the cooling process – a trip that's hard for a gas to make. The gas also needs to create a cooling effect when it enters the indoor evaporator coils, which become cold during a phase change that changes the liquid to a gas. To create that phase change, the gas coming out of the compressor first needs to become a liquid.
The condenser coils perform this phase change, which causes the surface of the coils to become hot in a reversal of the process that takes place in the evaporator coils. The refrigerant is then ready to move inside.
Potential Malfunction: Inefficient Phase Change
Condenser coils need to efficiently change the phase of all the gas refrigerant entering into the coils so that the evaporator coils receive the full supply for cooling. Loss of phase change efficiency can reduce the amount of cooling available and start to push warmer and warmer air out of your home vents.
The condenser coils can lose efficiency due to dirt or grime buildup on the surface, due to a crack that allows gas refrigerant to leak out, or due to a problem with the type and level of the refrigerant. If you are unsure of the cause, call in an air conditioning services company like Ron Hammes Refrigeration for a consultation and diagnosis. Fixing the inefficient coils as soon as possible can eliminate the efficiency loss before you really begin to feel the difference inside your home.
Potential Malfunction: Overheating Shutdown
As mentioned above, the condensing coils become warm during the phase change process. The warmth is kept in check by a nearby blower fan and by the properly balanced phase change. If the coils become too warm, the air conditioner's safety sensor would trip the unit and shut down as a precautionary measure. The unit would run normally until the coils become too hot and the system shut off.
Overheating coils can happen due to the same causes of efficiency loss: dirt, cracks, or refrigerant issues. But the problem can also stem from a malfunctioning blower fan though that cause is easier to diagnose if you simply stand by the unit while it operates and listen to see if the fan sounds normal. If you can't identify the problem, or need help with repairs, call in an HVAC repair technician.