How to Spot a Bad Air Conditioning Condenser

Mia Bevacqua
February 1, 2019

Much like a radiator, an air conditioning condenser is used to get rid of heat. But instead of working with the engine cooling system, the condenser helps cool the AC's refrigerant.

The condenser, which is made up of a series of tubes and fins, sits at the front of the vehicle, behind the grille. As the car travels down the road, air blows across it, cooling the hot refrigerant within. Gradually, the gas transforms into a liquid as its temperature is reduced.

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Signs of a failing AC condenser

When a condenser fails, it’s usually either because of leaking or clogging. These problems often result in the following symptoms:

  • AC doesn’t cool properly: Because the condenser removes heat from refrigerant, a problem with the unit will keep the system from getting cold.
  • Icy spots on the condenser: If the condenser is restricted, frost may accumulate near one end.
  • Refrigerant leaks: A condenser can develop a refrigerant leak, either from damage or age.
  • Warning lights: Some vehicles will flash the AC button or turn on a warning light if a problem is found. 
  • Improper AC system pressure: Mechanics use a set of pressure gauges to diagnose the AC system. A restricted condenser will typically increase the compressor discharge pressure.

How to fix the problem

A defective condenser should be replaced. The job is best left to an expert since professional equipment must be used to safely evacuate and recharge the AC system.

In some instances, other components such as the grille, bumper or radiator may need to be removed to access the condenser. Most professionals also recommend replacing the accumulator or receiver-drier to keep the system clean after service.  

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How does it work?

To better understand the role of the condenser, remember that heat always moves to a cooler state when possible. In other words, your air conditioner takes the heat from the cabin and transfers it to the outside air. Here’s how it works:

Liquid refrigerant starts to “boil” and expand as it enters the evaporator core. As the refrigerant expands, it pulls heat from the surrounding air. A blower motor pushes warm cabin air over the evaporator fins, and heat from this air is “transferred” to the refrigerant.

After that, the gaseous refrigerant leaves the evaporator and heads to the compressor. The compressor pressurizes the refrigerant and increases its temperature.

The refrigerant then leaves the compressor and enters the condenser, behind the vehicle’s grille. When the car is moving down the road, cool air blows through the condenser (when idling, an auxiliary fan is used). As a result, the heat is removed and the refrigerant turns back into a liquid.

On the final leg of its journey, the enters either a receiver-drier or accumulator. It then repeats the process.

Mia Bevacqua

About the Author

Mia Bevacqua is an automotive expert with ASE Master, L1, L2 and L3 Advanced Level Specialist certification. With 13-plus years of experience in the field, she applies her skills toward writing, consulting and automotive software engineering.

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