Five of these six signs mean your unit needs cleaning. One of them means a repair. None of them means you need a new aircon. Here’s how to tell them apart.
“It smells musty when I first turn it on”
This is the most common one. It almost always means mould or bacteria growing on the coil or the fan wheel inside. Those parts stay wet, and Bangkok is humid, so it’s a good home for both. The smell is worst in the first minute and fades as the unit runs.
A quick spray clean won’t fix this for long, because the spray can’t reach the fan wheel. A full clean takes the unit apart, so it can. Here’s the difference between the two.
“It’s just not that cold anymore”
Check the easy things first. Is the thermostat set where you think it is? Is the door shut, and is there a gap under it? Is the sun hitting that wall?
If all that’s fine, a dirty coil is the likely cause. Dust on the coil works like a blanket. It stops the unit pulling heat out of the air.
One case is different. If the unit blows warm air all the time, that’s usually a refrigerant problem. That’s a repair, not a clean, and we’ll tell you so rather than wash a unit that needs something else.
“The airflow feels weaker than it used to”
Dust builds up on the coil fins and on the fan wheel, so less air gets through. If the room takes longer to cool but the unit sounds the same as always, this is usually why.
It creeps up over months, so most people don’t notice until it’s well along. It’s common in the ceiling and cassette units in offices and serviced apartments around Sathorn and Silom. Those units sit above the ceiling, out of sight, so weak airflow is often the first thing anyone spots.
“There’s water dripping down the wall or pooling under the unit”
This is nearly always the drain pipe, not a refrigerant leak. Dust and mould narrow the pipe over months until the water can’t drain fast enough. It backs up and comes out where it shouldn’t. It’s the same buildup that causes the smell, further along.
We flush the drain pan and pipe on every full clean. This is the sign that gets worse fastest, because a half-blocked pipe blocks all the way in no time. If water is dripping right now, don’t wait for your next scheduled clean.
“I can see mould, or dark spots, near the vents”
If you can see it without opening the unit, there’s more inside that you can’t. Mould near the vents means the coil and fan wheel behind it are worse. Visible mould is a late sign, not an early one.
“It just looks dirty when I take the front cover off”
Dust on the filter or the front of the coil is normal after a few months, and on its own it isn’t urgent. It becomes urgent when you can see it from across the room, or when it’s been longer than the right interval for Bangkok since the last proper wash.
What to do about any of these
All of them point to the same fix, with one exception. A unit blowing warm air all the time needs a repair. Everything else on this list needs a full chemical wash.
That’s ฿1,200 for one wall unit, indoor and outdoor unit included. See the full price list. If more than one of these sounds like your unit, book sooner rather than later. The drain pipe is the one that turns into a real problem if you leave it.
Frequently asked
My aircon smells musty but only for the first minute. Is that really worth cleaning for?
Yes. The smell fading doesn’t mean the mould is gone. It means the first burst of air has passed and thinned out. The buildup causing it is still there, and it gets worse on its own, not better.
Is water dripping from my aircon dangerous or urgent?
Not dangerous, but deal with it soon. A part-blocked drain pipe blocks all the way fast, and left long enough the water can damage the wall or ceiling below the unit.