September 8, 2026 · Cairns Aircon Installers
Two identical systems, two identical houses, one works beautifully and one never feels right. Placement is usually the difference. It affects comfort, running cost, noise and how long the machine lasts, and unlike the brand or the capacity it is very hard to change once the holes are drilled.
The Indoor Unit
High on the wall, with a clear throw
Cold air falls. The head unit needs to sit high, typically near the top of the wall, so conditioned air can be thrown out across the room and settle down through it. Then it wants an unobstructed run. A tall wardrobe, an open door, a bulkhead or a ceiling fan blade sitting directly in the airflow path all break up the throw and leave you with cold and warm patches.
Aim it down the long axis of the room where you can. Blowing into a wall three metres away wastes half the machine.
Not directly over the bed, not straight at the couch
In a bedroom, being under the airflow all night is the single most common complaint about an otherwise good install. Put the head unit on a wall where the air passes over the bed rather than onto it, usually the wall the bedhead is against or the one beside it.
Same principle in the living room. Air moving across the seating is comfortable. Air blowing onto the back of your neck for three hours is not.
Away from heat and interference
Keep it clear of downlights, the kitchen, a television or anything else that puts out heat near the unit's return air intake, because the built-in sensor reads the air going in and will misjudge the room. Leave space above and around it for the return air path and for a technician to get the cover off later.
Think about the drain before anything else
This is the one homeowners never consider and installers should never ignore. The condensate drain runs on gravity and needs continuous fall the whole way to the outside. A position that gives no natural fall means either a pump (another component to fail) or a compromised drain line that will back up and leak water through your ceiling in a couple of wet seasons.
If an installer picks a wall you did not expect, this is very often why.
The Outdoor Unit
Shade beats sun, every time
The condenser rejects heat into the outside air. The hotter that air, the harder it works. A unit in full western sun on a Cairns afternoon is fighting the job it was designed for.
South or east facing walls, under an eave, or shaded by the building itself are all better. If natural shade is not available, a purpose-built cover with proper clearance helps, but it has to be built so it does not restrict airflow, which brings us to the next point.
It needs to breathe
Clearance is not optional. The unit needs open space at the back for air in, and a clear path in front for hot air out. Boxed into a narrow side passage, tucked behind a fence panel, or wedged under a low deck, it re-breathes its own hot exhaust and efficiency falls off a cliff. Check the manufacturer's clearances and treat them as a minimum, not a target.
Also keep it clear of the garden. Grass clippings and leaf litter blocking the coil is one of the top causes of a system tripping the circuit breaker.
Salt air on the coast
If you are in Palm Cove, Trinity Beach, Yorkeys Knob, Holloways Beach or anywhere else close to the water, distance from the surf and the prevailing salt spray genuinely affects how long the outdoor unit lasts. Put it on the sheltered side of the building where you can, and look at models with better coil coatings. It is worth the conversation at quoting stage.
Noise and the neighbours
Outdoor units are much quieter than they used to be, but they are not silent. Avoid mounting one directly outside your own bedroom window, or hard up against a neighbour's. On a narrow suburban block, the wall you choose matters. Vibration through a lightweight timber wall carries further than people expect.
Fixings and cyclone rating
This is Far North Queensland. Mounting has to be specified and fixed for the wind region, whether that is a ground slab, proper wall brackets into structure, or a stand. Brackets into unreinforced render or a couple of dynabolts into the wrong substrate is not adequate here, and it is one of the things we look hardest at when we are asked to assess somebody else's install.
Access for servicing
Somebody has to reach it once a year with a hose and equipment. A unit on a second-storey wall with no access, or one buried behind a locked gate and a water tank, will get serviced less often and cost more when it is. Easy access is a small consideration at install and a recurring benefit for the life of the system.
Keep The Pipe Run Short
The refrigerant line between indoor and outdoor units has a maximum length and every extra metre costs a little capacity. Manufacturers publish limits and good installers keep well inside them. Pairing the two units on opposite corners of the house because it suits the cosmetics will cost you performance for the life of the system.
Common Mistakes In Cairns Homes
- Queenslanders: raked ceilings and high-set construction change the drain fall and the throw. Worth planning properly rather than defaulting to the nearest external wall.
- Block homes: the wall build affects fixing method and core drilling. Not every wall is a good candidate.
- Renovations: systems get positioned around where the old unit was rather than where the room now needs it after walls moved.
- Second storey outdoor units installed with no thought to how anyone will service them.
Get It Assessed On Site
None of this can be settled from a floor plan. We look at the room, the wall construction, the drain path, the outdoor position and the servicing access as part of quoting, and we will tell you where we think it should go and why.
See our split system installation page for how we do it, or request a quote and we will come and look at the space.