Car Air Conditioner Repair: Replacing the Evaporator

  • 4-10 hours
  • Advanced
  • 100-400
What You'll Need
Replacement Evaporator
Service manual
Allen Wrenches
Drive Sockets
Wire Cutters
Vacuum Pump and Gauge
Coolant

A bad evaporator is a common problem with a car's heating and cooling system. However common, many people call a mechanic when their evaporator fails because it seems like a tough job. Instead of spending money to get it repaired, you can follow the guidelines below to easily do the job yourself.

Step 1 – Familiarize Yourself with the Air Conditioning Evaporator

The auto air conditioning evaporator is located behind your dashboard, and it is crucial to the car's air conditioning and heating system. It cools and dehumidifies air in the passenger compartment of the car.

Freon enters the bottom of the air conditioning evaporator as a high-pressure fluid. The coolant flows through the evaporator coils and causes a cooling effect. A fan located behind the evaporator coils blows the cold air into the vehicle.

The dehumidifying process takes place when the warm air inside the car comes into contact with the cold evaporator surface. This warm air passes through the fins of your evaporator that causes the Freon coolant to boil. As it boils, it absorbs a great amount of heat. On humid days, you will see water dripping from under your vehicle; this is normal.

When getting the car serviced, having your evaporator checked should be a part of your auto's routine checkup and maintenance. If a leak check fails, the evaporator should be replaced. You will smell a strange odor once you turn on your air conditioner. That smell is a good indication that the evaporator needs to be replaced. Replacing the evaporator requires you to remove many parts to access.

Step 2 – Locate the Evaporator

Use a service manual to locate the evaporator and follow instructions for its removal.

Step 3 – Remove the Evaporator

Flush all coolant from the system and place the liquid into an approved recycling unit. The refrigerant must be discharged before the evaporator can be remove because it is dangerous to remove parts when the refrigerant is still in the system. You must bleed, or discharge, the system first. This operation should be performed by a licensed refrigerant handler.

Remove the liquid line connection that goes to the evaporator, and then remove the heater hoses from the core. Next, remove the air conditioning and heating unit from under the dashboard, which is located under the instrument panel. Turn the unit upside down to remove the screws that hold it together. Next, remove the center-adapter duct and the screws. Flip the unit back over to take the upper half of the “housing” off. Remove the evaporator from the lower housing case. Check for damage to the housing that holds the evaporator for any cracking or wearing, and be sure there are no missing pieces to the housing. Replace any damaged or worn pieces.

Step 4 – Replace the Evaporator

Lastly, install the new evaporator system by following all the steps above in reverse order, and then fill the system back with coolant.