Warning signs of a bad A/C evaporator

What you need to know about A/C evaporators

The evaporator might just be the most important part of your car’s A/C system. Well, every part is important, but the evaporator is what determines the air temperature you feel inside the cabin — which is effectively what keeps you cool all year long.

Essentially, the main role of the evaporator is to absorb heat, remove humidity from the air, and to distribute this cooling effect to the inside of the car via the blower fan. Usually referred to as the coil or core, the evaporator works together with the expansion valve and blower fan to circulate cool air.

If the evaporator fails, it will need to be replaced to keep the rest of the system running optimally. This is a common problem faced by car owners, especially those with older vehicles. Thankfully, there are ways you can identify problems before they get too dire.

Cooling specialists at Natrad are here to help you keep your air conditioning system in tip-top shape. With a huge range of evaporators available, Natrad will help find the right part for your car’s air conditioning system.

How does a car’s aircon evaporator work?

cool air conditioning As stated before, the evaporator is responsible for creating cool air. Except saying ‘creating’ is somewhat inaccurate, since the evaporator actually functions as more of a removal tool for humidity and heat. So, how does it do this?

As refrigerant circulates the air conditioning system, it passes through the expansion valve before entering the evaporator. After this, the refrigerant passes through the tubes of the evaporator much like how coolant passes through a radiator. Inside the evaporator, the liquid refrigerant evaporates into a gas state and becomes very cold.

Inside your passenger cabin, warm air that passes across the cold evaporator fins is cooled. This heat exchange happens due to temperature conducted through the metal of the evaporator. The now cold air exits the evaporator into the cabin of the car via the blower fan, where you finally feel that cool, dry air.

Moisture in the air also condenses on the cold metal surface of the evaporator and eventually drips into a collection drain tube. These drips may create a small puddle under your stationary car. This is completely normal and not a cause for concern.

This cycle then repeats while the air conditioning is switched on, continuously providing you with cool dry air inside your car.

Why are evaporators so important?

Car air conditioning evaporators are vital because they cool the air inside your car. They work by turning liquid refrigerant into gas that produces the temperature drop used to make cold air, keeping your car comfortable in hot weather. Without them, your car’s AC system simply wouldn’t work.

However, since it’s located behind the dashboard, it can be hard to get to, making replacement a big job. So, how can you prevent failure?

Make sure to regularly service and check your air conditioning system. Natrad is here to help you look after your car. 

Warning signs your evaporator needs replacing

  1. Weak airflow or warm air: weak airflow could result from a blockage or a blower fan issue. Warm air indicates a potential problem with refrigerant that might be due to a leaking evaporator.
  2. Strange/sweet smell: refrigerant has a sweet aroma, and may enter the cabin from a leaking evaporator. This smell may get more intense when the A/C is switched on.
  3. The Compressor doesn’t activate: A leak may result in reduced pressure, which means the compressor will not activate or be able to circulate refrigerant around the system and to the evaporator.
  4. Inconsistent air temperature: this may indicate a damaged evaporator.

Possible reasons for evaporator coil failure


Over time, exposure to moisture and contaminants in the air can cause the air conditioner’s evaporator coil to corrode. This corrosion can weaken the structure of the evaporator, leading to leaks and reduced cooling efficiency. Use of corrosion-resistant materials can help mitigate this issue.


Evaporator coils can become clogged with dirt, debris, or mould buildup. This restricts the flow of air and reduces the efficiency of the cooling process. Clogging can result from inadequate air filtration in the HVAC system. Cleaning dirty evaporator coils and changing filters regularly can prevent this problem.

Degrading of a seam or weld

The seams or welds in an AC evaporator can degrade over time due to the constant expansion and contraction of the coils as the system cycles on and off. This can lead to small cracks or holes, causing refrigerant leakage and a loss of cooling capacity. Proper installation and use of quality components can help prevent seam or weld issues in your evaporative cooling system.

Wear and tear

Like any mechanical component, an AC evaporator can succumb to wear and tear over years of use. The constant cycling of the system and exposure to temperature fluctuations can cause the evaporator to weaken, leading to a leak. 


One of the most common reasons for failure in vehicle air conditioning units is refrigerant leakage. Over time, the seals, gaskets, and connections within the AC system can deteriorate, leading to leaks. When refrigerant levels drop, the AC system becomes less effective at cooling. Detecting and repairing leaks promptly can help maintain the efficiency of the AC system and prevent further damage to the evaporator. 

Evaporator repairs and replacement at Natrad

If an evaporator has failed in your car’s AC unit, it will need to be replaced. This is often accompanied by an air conditioning system recharge and possible replacement of other components.


Because the evaporator is part of a system with refrigerant inside, this is not something you can tackle yourself. Replacement should only be handled by a professional, especially if the dashboard needs to be removed. 

with refrigerant inside, this is not something you can tackle yourself. Replacement should be handled by a professional, especially as sometimes the dashboard may need to be removed.

If you’re in need of a replacement evaporator or simply want to identify an air conditioning unit problem, experienced Natrad technicians across Australia are here to help. Contact us today for all your air conditioning needs.