Your car's air conditioning system is similar to a home central or mini-split air conditioning system but on a much smaller scale. Like these residential systems, your vehicle has condenser and evaporator coils, a compressor, and refrigerant plumbing to transport heat away from your cabin. Any of these parts can potentially fail, leaving you sweating on your way to work on hot, sunny days.

Two potentially common points of failure are the evaporator coils and the compressor motor. Understanding which one is causing your problems can help you prepare for the repairs you'll need to get your car's cabin cool and comfortable again.

How Your Evaporator and Compressor Work

Your compressor is the primary mechanical component in your air conditioning system. This part pressurizes the low-pressure vapor that returns from your cabin, allowing it to release heat as it moves into the condenser coils. The compressor effectively acts as a pump, ensuring that refrigerant continually moves from the high side of the system to the low side.

On the other side of the system is your evaporator coil. You can think of your evaporator as a radiator that works in reverse. Cold liquid refrigerant passes through the evaporator coils, absorbing energy from the warm air that passes over it. The colder air from the evaporator then cycles back into your cabin, reducing the temperature and keeping you comfortable on hot days.

The Symptoms of a Failing Evaporator

Your evaporator doesn't have any moving parts, but it does contain many tiny refrigerant passageways and aluminum fins. Since air must pass over the evaporator, it can accumulate dirt, dust, and debris over time. The cold refrigerant also causes water to condense out of the air, meaning there's usually a reasonable amount of moisture draining from the coils.

These two issues can eventually cause the evaporator to corrode and leak refrigerant. The coils will likely freeze if this occurs, preventing them from efficiently absorbing heat. You may notice humid air from your AC, or your system may briefly produce cold air before blowing warm, tepid air into the cabin. Note that leaks elsewhere in the system can also cause similar symptoms.

The Symptoms of a Failing Compressor

A faulty compressor will often produce more dramatic symptoms than a leaky evaporator. If your compressor is on its way out, you may hear a loud grinding or clunking noise when it turns on. You may be able to confirm this problem by switching the AC on and off with the hood open while the car is idling. If you hear a loud clunk when the AC engages, that can signal compressor trouble.

A failing compressor can also struggle to start or shut down prematurely. If your AC only runs briefly and sounds like it's struggling to keep going, that's another good indication that your compressor is on its last legs. This part can be costly, so always take your car to an AC shop if you suspect trouble. Quickly addressing AC problems can often help you avoid causing permanent damage to your compressor.

To learn more information, reach out to car air conditioning repair services near you.