If your aircon has been unused for months — due to travel, renovation, or seasonal changes — you might be tempted to switch it on immediately. However, turning it on without preparation can cause breakdowns, water leaks, or electrical faults. Because Singapore’s humid climate and dust buildup affect aircon systems, restarting the unit incorrectly can lead to costly repairs.
Fortunately, there are expert-approved steps to bring your aircon back to life safely and smoothly.
1. Check and Clean the Air Filters First
After months of inactivity, dust and moisture can build up on your aircon filters. As a result, airflow gets restricted, which puts extra strain on the system.
What to do:
Remove the filters
Wash them with mild soap and water
Let them dry completely before reinstalling
Why it matters: Clean filters allow your aircon to breathe properly and help prevent the compressor from overheating.
2. Inspect for Dust, Mold, and Musty Smells
Because Singapore’s humidity is high year-round, moisture can settle inside your aircon even when it’s off. As a result, mold may grow on the coils, blower wheels, and drainage areas.
Before turning it on:
Shine a flashlight into the unit
Look for dark spots, dust buildup, or white fuzzy growth
Smell for any stale or sour odors
If you notice anything suspicious, it’s safer to schedule a professional chemical wash before using the aircon. This ensures your unit is clean, safe, and ready to run efficiently.
3. Examine the Outdoor Unit Carefully
Next, inspect the outdoor condenser. During periods of inactivity, leaves, soil, insects, and even small animals can find their way inside the unit.
Check for:
Blocked vents
Debris around the fan
Oil stains (which may indicate refrigerant leaks)
Keeping the outdoor unit clear ensures proper heat release and prevents the compressor from overworking. As a result, your aircon runs more efficiently and lasts longer.
4. Test the Circuit Breaker and Wiring
Before powering up, make sure no circuit has tripped. Also, check for signs of rust, moisture marks, or burnt smells around the electrical components.
Why this matters: Electricity and Singapore’s humidity don’t mix well. By taking these precautions, you can prevent short circuits and protect both your aircon and your home.
5. Run the Aircon in Fan Mode First
Instead of turning the aircon straight to Cool Mode, start with Fan Mode for 15–30 minutes. This allows you to:
Dry internal moisture
Clear trapped humidity
Reduce sudden thermal shock to the coils and compressor
Afterwards, you can safely switch to Cool Mode, ensuring your aircon starts without strain.
6. Set a Moderate Temperature (Not Too Low)
When restarting your aircon, avoid setting it to 16–18°C right away. Doing so forces the compressor to work too hard, too quickly.
Recommended setting:
👉 24–26°C for the first hour
This helps gradually stabilize the refrigerant cycle and lowers the risk of freezing the coils.
7. Listen for Unusual Noises
As the system starts up, listen carefully to how your aircon sounds. Often, unusual noises can indicate deeper problems.
Common warning sounds:
Rattling: Loose parts or debris
Whistling: Air leakage
Humming: Strained electrical components
Grinding: Fan motor issues
If you hear anything unusual, turn the unit off and schedule a professional check-up before more damage occurs.
8. Inspect for Water Leaks After 30 Minutes
Finally, inspect the indoor unit and drainage pipe for water dripping. Over time, algae or sludge can clog the drainage line, especially after long periods of inactivity.
If you notice any leaks:
Turn off the unit
Avoid using it until a technician clears the drain
By doing this, you prevent water damage to your walls and ceilings and keep your aircon running safely.
When Should You Call a Professional Before Restarting?
You should contact an aircon specialist if:
✔ The aircon smells musty
✔ The outdoor unit is dirty or blocked
✔ You see oil stains around the condenser
✔ The unit was unused for 6 months or more
✔ The system is old (8–12 years)
✔ You hear strange noises during startup
A quick service now can save you from a breakdown later.
When Should You Call a Professional Before Restarting?
At Lion City Air Conditioner Services, we ensure your unused aircon restarts safely without causing damage.
We specialize in aircon servicing, repair, chemical wash, and installation in Singapore, helping your unit run smoothly after long periods of rest.
📞 Call us at +65 8818 5781
🌐 Book your service online at lioncityaircon.sg
Restart your aircon the right way—and prevent breakdowns before they happen.
