What should you do about a rusty aircon bracket?

Aircon bracket rust: why it matters

Yes, rust on the parts that hold the outdoor unit up can be dangerous. The unit is heavy and mounted outside the flat, often high up. If the bracket, its bolts or the wall fixings weaken, the unit could fall. HDB warns that a falling outdoor unit can cause serious injury or death. It also says flat owners are responsible for maintaining their aircon units, and that owners face penalties if a unit or its supports fall for lack of maintenance.

Not all rust carries the same risk. Aircon outdoor unit rust on the casing panels is mostly a sign of age and weather. Rust on the bracket arms, the welds, the bolts that hold the unit to the bracket and the anchors in the wall is different, because those parts carry the load.

Signs that deserve a closer look include:

• flaking or bubbling metal on the bracket arms
• rust around bolt heads, nuts or welded joints
• orange rust streaks on the wall below the fixings
• a unit that sits at an angle or rattles more than it used to

Rust does not reverse on its own, so treat it as a maintenance job to book, not something to watch for years.

What to check

HDB's aircon care guide asks owners to inspect their aircon regularly. Its points to check are:

• brackets are on concrete or brick walls only, not timber frames
• stainless steel brackets are free of corrosion and rust
• there is no leaking
• condensate piping runs into the flat to a floor trap

Water matters too, because a unit that drips onto its own bracket keeps the metal wet. If you notice water under the unit, see our guide to aircon outdoor unit dripping.

1. Look from inside. Check the bracket through the window. Never lean out or reach for the unit.
2. Photograph the bracket. Take clear photos of the bracket, bolts and wall fixings from a few angles, so you can compare them over time.
3. Note rust on bolts and welds. Look closely at bolts, nuts, welded joints and the points where the bracket meets the wall. Flaking metal or rust stains there matter most.
4. Ask your servicing technician. At the next servicing, show the technician your photos and ask them to check the bracket and fixings up close.

Replacing a bracket

HDB suggests asking your aircon servicing technician whether rusty brackets need replacing. The technician can tell you whether light rust only needs watching, or whether the bracket, bolts or fixings call for an aircon bracket replacement.

Replacing a bracket usually means taking the outdoor unit down and mounting it again, so ask the company how it follows HDB's rules for aircon installation works. Under HDB's renovation guidelines, air-conditioners must be installed by a BCA-trained air-conditioning condensing unit installer (BCA is the Building and Construction Authority), and an installation report must be submitted to the HDB Branch within 14 days after installation. The guidelines also say the aircon ledge is only for the condensing unit, with rubber padding under the unit.

Before you agree to the job, ask the company:

• whether the quote covers taking the unit down, refitting it and removing the old bracket
• what material the new bracket is made of
• whether an installation report is needed for your job, and who submits it

The cost depends on the job, so ask for a written quote that lists each item. For the installation side in more detail, see our guide to HDB aircon installation rules.

Rust on the outdoor unit itself

Surface rust on the casing is the least worrying kind. It can usually be cleaned off and touched up with paint. Leave any work on the outside of the unit to the technician.

Rust on the coil fins or the base pan is different: it is a sign of wear, not just a cosmetic mark.

Before you pay for a big repair, check how old the unit is. Ask the technician to compare the repair with replacing the unit, and to put both options in writing. The cost depends on the job, and you can compare companies offering aircon repair before you decide.

Buying a resale flat

Check the brackets before you buy, not after. Once the flat is yours, so is the job of maintaining the aircon units and their supports.

At the viewing, look at each outdoor unit through the window and photograph the brackets and fixings. Ask the seller when the units were last serviced and whether any bracket has been replaced. Heavy rust on a bracket is not a reason to walk away, but it is a cost to plan for and worth raising before you agree on the price.

Our resale flat aircon checklist covers the other points to check on a second-hand flat's aircon.

Questions