How To Flush an Automotive AC System

Flushing the AC is important for proper functioning. AC flush is a process that involves compressed air being used to send a special solution throughout the AC system. The solution goes through all of the parts and cleans the system. Any kind of contaminants and particles that may cause problems to the AC systems are flushed out with the help of this solution.

AC flush can be performed when the AC system is opened or when the AC compressor is being changed. While flushing the AC system of your car may seem like an easy thing to do, it is often neglected by most car owners. Ultimately, the contaminants and particles in the AC systems cause a myriad of problems that could have been avoided.

During a thorough AC system flush, the evaporator, condenser, and all of the AC lines are properly cleaned with the help of the substance. The accumulator and the compressor, however, are changed.

Why Do AC Systems Require Proper Flushing?

The automotive AC is a closed system and is generally self-contained. It is majorly composed of oil and refrigerant. The oil is used to lubricate the compressor of the AC system, and the refrigerant gives the system its conditioning properties. Whenever the closed system is opened, there is a high risk of harmful contaminants entering into the AC system.

In the case where an AC compressor fails to work, the contaminants go through the compressor into the system and can cause many problems. Once the contaminants come into the system, they start damaging a lot of components present in there. Even a fully functioning, new AC system may cease to work if it is affected by any contaminants. Contaminants can also cause a newly installed compressor to fail.

When Should You Flush Your AC System?

Whenever you get your AC compressor changed, an AC flush is performed. Moreover, whenever the closed AC system is opened for any reason, an AC flush should be performed as the risk of contaminants increases, and it is almost certain that the contaminants will enter every time. If you operate on an AC system that hasn’t been working for a long time, you’ll need to perform an AC flush because the system will not recharge properly when you don’t flush it.

Before attempting to recharge an older AC system, you will need to use a flushing tool that will send a substance in the system, cleaning out the evaporator, the condenser, and the AC lines. Once you have flushed the AC system, you can put the hoses back on. Attach the compressor and the new accumulator, and your system is flushed. It is always better to change the receiver drier or the accumulator every time you open the AC system.

How To Flush The AC System:

To properly flush the AC system, you need to follow the steps mentioned below.

  • Getting The Car Ready for The Flush:

Mostly when an AC System is flushed, you will need to park the car. The AC system should be opened, and the lines that are present at the compressor should always be disconnected. Then, remove the accumulator or the receiver drier from your AC system since it is going to be replaced. Then, remove all of the AC lines that lead to the condenser and the evaporator.

  • Starting With The Evaporator:

The first thing to be decontaminated in an automotive AC system flush is the evaporator. The evaporator is the fitting that leads into the firewall, and it is the part that will be flushed before any other part. Use the heater hose to slip over the threaded fittings known as the evaporator. Remember to keep a bucket at hand. Feed the hose that you have into the empty bucket.

Now, the flushing tool that you have will be used to flush the special solution into the evaporator. This will be done by injecting it into the other hose inlet. Then, the air and the flush solution will be quickly drained out from the evaporator, taking out any contaminants that might have been in the system.

  • Flushing The Condenser:

Next, you will need to flush the condenser. Put the heater hose on the fitting that is below the other one and is located on the condenser. Turn the flushing system on and blast the flush solution into the condenser. Then, the solution will be drained out of the condenser carrying any contaminants.

  • Flushing the AC Hoses:

Before these steps, taking off the AC hoses is essential. Take the AC hose that you removed before you started the process and put one of its ends into an empty bucket. Turn the flushing system and blast the solution throughout the house. Remember that if you still have a receiver/accumulator attached to the hose, you might want to remove it since it is going to be replaced anyway.

However, for the systems that have a hose with a built-in accumulator, you will need to replace the hose as a whole.

  • Attaching The Hoses:

Once you have flushed all the parts of the AC system, you can easily reattach the hoses with new o-rings. The new compressor installed will also be attached.

  • Checking The System:

After performing all the mentioned steps, the AC system is brought under a vacuum. This is done to make sure that there are no leaks. Moreover, it removes all atmospheric air from the AC system. After checking for leaks and atmospheric air, the AC system is ready to be recharged using the perfect amount of refrigerant and oil.

The Takeaway:

Flushing the AC system of your car should not be skipped. Especially when you are servicing the AC compressor, the chances of damage increase. In order for an AC system to work properly, there must be zero contaminants present in it. The only things present in the AC system should be refrigerant and oil. Any change in quantities can end up damaging your AC system. Now that you know the steps to follow when flushing an automotive AC system, you’ll have no problems taking care of your AC system.  

Daniel Wood

Daniel, who is a mechanical engineer and hobbyist mechanic by profession has been specializing in electronic equipment for the past four years. He worked as an engineer at one of these manufacturing plants that specializes exclusively on this type equipment before opening up his own shop where he does research into different machines all day long!