Air conditioning
What does dry mode do on an air conditioner?
Dry mode takes moisture out of the air without chilling the room. It suits the sticky, overcast days the Illawarra coast gets plenty of, when the temperature is fine but the house feels close.
4 min read
The short answer
What dry mode actually does
Every air conditioner removes moisture while it cools. Warm, damp air hits the cold indoor coil, water condenses on the fins the way it beads on a cold glass and the drain carries it away. In cool mode the system is chasing a temperature, so it works hard and switches off once it gets there, sometimes before it has done much about the humidity.
Dry mode changes the priority. The system runs the fan slowly and cycles the compressor to keep the coil cold without driving the temperature down, so more air spends more time on the coil and more water comes out of it.
Dry mode against cool and fan
| Mode | What it does | Use it when |
|---|---|---|
| Dry | Removes moisture, lowers the temperature slightly | Muggy, overcast days in the low to mid twenties |
| Cool | Brings the room down to a set temperature and removes moisture on the way | Hot days or when the room needs to cool quickly |
| Fan | Moves air without cooling or drying it | Mild days when you just want air moving |
When dry mode is the wrong choice
On a hot afternoon dry mode cannot keep up, because it is deliberately holding back. Switch to cool mode and set it to 24 to 26 degrees. It also does little in a cold room, where the air holds less moisture to begin with.
If a room stays damp whatever mode you use or the system smells musty when it starts, the moisture may be sitting in the unit rather than leaving it. Our guide to why an air conditioner smells covers what that points to.
A clear drain matters more in dry mode
Dry mode exists to pull water out of the air, so on a humid day the drain carries a steady flow the whole time it runs. A drain half blocked with dust and slime copes in cool mode and overflows in dry mode, which is when people first notice drips on the wall under the indoor unit.
A yearly air conditioning service flushes the drain and tray along with the coil. For what the system costs to run, our guide to air conditioner running costs shows how to work it out from the rate on your own power bill.
Common questions
- Is dry mode cheaper to run than cool mode?
- Usually a little, because the compressor runs slower and the fan runs at low speed. The saving depends on the model and the room. On a genuinely hot day cool mode does the job faster, so it can end up using less overall.
- Can I leave dry mode on all night?
- Yes, on a humid night it is a comfortable setting to sleep with. If the room gets too cool, switch to cool mode with a higher temperature or use the sleep function instead.
- Does dry mode heat the room?
- No. Dry mode always cools slightly while it removes moisture. For damp winter days, use heat mode, which also dries the air as it warms it.
- Is dry mode the same as a dehumidifier?
- It does a similar job in a room that is also warm. A dedicated dehumidifier works better in a cold, damp room, because it removes moisture without cooling the space further.