Flushing Your Car's AC System

What You'll Need
Wrench
Aerosol air conditioning flush
Rag or cloth
New accumulator (optional)

Heavy use in warmer months can really wear on your car’s AC, causing buildup in the system that emits unpleasant odors and can significantly increase the energy it takes to run. To save fuel and limit the need for future repairs, flush your system at least once a year.

Prepare Your Vehicle for the AC Flush

Park on even ground somewhere safe where you have room to work, leaving the engine in idle and engaging the brake. Ensure the air conditioning system is turned on.

Pop the Hood

The hood of the car will need to be open for this process, as this is where you’ll be doing all the work.

a gloved hand working on a car AC unit

Take Your AC Apart

This may sound like a big task, but it’s not as scary as it sounds. Remove the hoses, evaporators, condensers, and other air conditioning components from your car. This will grant you the access to the inside of the system that you need in order to effectively flush it.

Flush Each Piece

Using an aerosol air conditioning flush (available online or at most hardware stores), carefully flush each individual piece of the system out. This will push debris and grime out of each component. It’s important to do these pieces one by one to get the most out of this process. Flush each component from both sides to get out the maximum amount of debris.

In some cars, the AC system is accessible through the dashboard.

flushing AC in a car

Wipe the Pieces Down

After the flush is over, use a clean cloth to wipe each piece down thoroughly.

Check the Ducts

Stemming from the zig-zag like tubes that make up your evaporator, the large tubes that are the “ducts” of your AC unit should be checked for leaks at this step of the process. If you find any holes, use duct tape to plug them. This prevents wasted energy, as air pushed to the system can leak out of those holes if they’re left open.

Replace the Accumulator

A standard accumulator should last for 10-15 years, but if your car is producing very little cold air, or the AC air smells funny, you might want to replace your accumulator at this stage.

Shaped like a coffee can, your car’s accumulator lives up to its name by “accumulating” debris, sifting it out from the engine and taking in condensation as it prepares the air to be pushed through your vehicle via the AC system. The more dirt, dust, and debris inside of this component, the less efficiently it will work.

New accumulators run around $40 as of this writing, and are available online or at most auto parts stores. Make sure the one you buy is compatible with the make, model, and year of your car. To install your new, clean accumulator, bolt it down where the old one was and reattach all components.

For more on AC flushing, check out this in depth discussion on our Doityourself Forum!