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How to Prevent Corrosion on Air Conditioner Outdoor Units

Author Rod Marchant-Smith | Peninsula Air Conditioning

Frenchs Forest resident, Michelle asks

“We’ve noticed a fair bit of rust on our outdoor air conditioning unit and have concerns this might affect it in some way. Is this normal? What can we do to protect the unit?”

Air conditioning outdoor units are usually exposed to the harsh Australian climate.  Over time this can result in a great deal of corrosion and wear, especially for residents living in coastal areas, as the systems are generally exposed to salt in the air through rain or mist.  To prevent corrosion and other forms of wear and tear, manufacturers apply anti-corrosive coatings.  However, the manufacturer’s warranty doesn’t cover damage or breakdown caused by weather exposure.

If you have concerns about the corrosive effects on your air conditioners outdoor unit, there are additional precautions you can take to mitigate the risk of damage or failure.

What some residents choose to do, is to cover or enclose the unit to protect it from the weather.  We recommend against this as this can inhibit airflow which can cause problems with the performance of the unit as well as potential overheating.

So, what are your options?

The first solution we recommend is relatively simple and it requires spraying an anti-corrosive product on to certain parts of your system.  Action Corrosion is a product that can be used for steel protection.  Applying it will involve removing the cover of the outdoor unit first to access vulnerable parts that need to be coated.  You could easily make this part of your regular home maintenance to prevent rust or corrosion forming or organise this during your next maintenance service.

We can also arrange for the unit to be treated with corrosion protection by a company called Blygold, which offers HVAC coatings and other services.  Blygold is the leading proponents of anti-corrosion in HVAC and marine applications and a company we recommend.  Blygold essentially takes care of everything.  They remove the panels and spray the inside parts of the unit to protect it from the elements and to ensure the system works efficiently.  The great thing about this service is that it comes with a one-year guarantee.  If you want an extended guarantee you will need to procure the services of Blygold independently and arrange a maintenance program through them.

We’ve seen very good results when it comes to corrosion protection.  One of our clients had a Daikin outdoor unit treated by Blygold and after nine years it is still in excellent working condition.  In terms of pricing, you can expect to pay between $400 and $700 for single fan units, but it’s a worthwhile investment.  Replacing your air conditioner as a result of damage from the elements is far more costly, which can often result in thousands in comparison.

If your air conditioner breaks down due to rust or corrosion, it’s unlikely we’ll be able to repair the unit.  Rust can often cause quite a lot of damage to the fan coil which affects the efficiency of the system.  When the fan coil becomes corroded the fan won’t be able to regulate heat distribution.  Corrosion can also cause dangerous electrical faults.  If your outdoor unit becomes too badly corroded, the only option would be to replace it.

Have you noticed signs of rust?

If you’ve spotted signs of rust on your outdoor unit, there will likely be internal corrosion too.  Book a service so we can inspect the unit and explore what your options are if we find evidence of damage.

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