An air conditioning system is a rather complicated piece of machinery. A multitude of compressors, pistons, and other mechanical parts all work in tandem with refrigerants and oils to ensure proper temperature control can be achieved in a home or car with relative ease. Of course, this means there’s a lot to consider when it comes to repairing or modifying any given A/C system. Many technicians will recommend an A/C flush to be performed during the replacement of an A/C system or its related parts.

But then, what exactly is an AC flush, and is it actually necessary? Well, let’s get to the bottom of it, shall we?

What’s an A/C flush?

Any given system is sure to become contaminated over time, with A/C systems being no different. Even the smallest granules of dirt can significantly impair the ability of an air conditioning system to work properly. An A/C flush is when a liquid solvent is forced through the system under pressure to remove all of the accumulated contamination to return the system to like-new functioning.

Why should a system be flushed?

Typically, a flush is sought during routine maintenance of the system or after a compressor failure. In the event of an A/C compressor failure, small metal shards will be sent throughout the system that can cause blockages to the system. Not only that, over the course of any A/C system’s lifespan, it’s likely that small amounts of dust and debris will be introduced to the system. It doesn’t take a lot of debris for the small passageways of an A/C system to become clogged. What might seem like an inconsequential amount of debris could be catastrophic if left in place. Therefore, flushing is necessary to ensure proper continued function.

Is the entire system flushed?

A few components of the system aren’t to be flushed under any circumstances. These include driers and accumulators, A/C compressors, muffler assemblies, orifice tubes, as well as expansion valves. Most of the time, the compressor is removed, and the oil is drained if the compressor itself isn’t being replaced, while the other components are fully replaced after the flush due to them being unusable afterward. Luckily, these components are very easy to replace and aren’t particularly expensive in the first place.

What exactly is flushed, then?

There’s still a lot more system to be flushed than the things you’re avoiding in the step above. First, the AC hose from the compressor to the condenser must be flushed as it’s likely some metal shavings have made their way in there if there was a compressor failure. Next, the condenser itself is flushed, with most condensers being designed with flushing in mind. Occasionally, a condenser will be removed to be primed with the flushing agent to ensure a more comprehensive clean. The final two components to be flushed are the high side liquid hoses as well as the evaporator. However, the evaporator should only be flushed in cases of extreme contamination.

When should the A/C system be flushed?

Any time that any work is being performed on your A/C system is a wise time to get your system flushed since it’s already being accessed. However, if you’re the type to only want to do something if it’s absolutely necessary, then, only when a condenser or compressor is being replaced should you consider flushing your system. A clean system is much less likely to fail, and it only takes about 1/10th of a teaspoon of dirt to fully gum up your system. It’s highly recommended that you play things safe and always opt for the A/C flush whenever the system is being repaired or worked on in any capacity. While it might seem like something you can skip, it isn’t recommended since you risk a more catastrophic failure down the line, thanks to the passageways having been blocked with dirt. Overall, a flush ensures efficiency, as well as the lifespan of any given A/C unit.

How is an A/C flush performed?

Many technicians use a simple AC flush kit that uses a pressurized system to force a flush solvent throughout the entire system. This ensures a stellar clean that reduces the chances of failure due to debris as best as current technology allows. It’s essential that the flushing solvent be completely removed from the A/C system after flushing. This is typically accomplished by using nitrogen to dry out the system post-flush.

A flush kit is typically made up of three items. The first item is, of course, the flush liquid to be used. The liquid being used needs to be compatible with the refrigerant used in the system, as well as fully removed afterward. The other two items would be the flush hose that carries the flush liquid, with the last item being the compressed air used to circulate the liquid throughout the system.

Once the flush has been completed, nitrogen will be then circulated throughout the system to ensure the complete removal and drying of any remaining flushing liquid within the system.

Conclusion

A/C flushing is done mostly as a preventative maintenance measure or to restore an A/C system to its original condition after a compressor/condenser failure. It’s a relatively simple procedure that should be done any time there’s an opportunity since there’s much to gain and not much to lose, besides time and a small monetary investment to get it completed. While it’s a relatively simple procedure, it should only be done by qualified technicians to ensure that no further damage to the system is made, as well as to ensure that the flushing agent has been properly dried and removed from the system. The nitrogen used to dry out the system post-flush is what stops most people from being able to comprehensively flush their A/C system themselves. Just know that the A/C flush your car mechanic is trying to sell you on is just a routine procedure, and not some made-up term meant to squeeze a few extra dollars out of your wallet.