Think you don’t need to maintain your air conditioner during winter? That’s a mistake! Before switching it off for the season, proper maintenance is crucial to prevent mold and bacteria buildup — so you won’t be caught off guard when summer arrives. Just like personal care, regular maintenance keeps your air conditioner performing at its best.
In this guide, we’ll explore the hidden risks of neglecting maintenance, expert cleaning timelines, and essential homecare tips — helping Hong Kong households improve indoor air quality, save energy and extend their unit’s lifespan.
3 Common Problems When You Skip Air-Conditioner Maintenance
Mould Odor When You Turn It On
That musty smell isn’t “just the weather” — it’s caused by lingering moisture and built-up dust inside the system, creating ideal conditions for mould and microbial growth.
When the unit starts up, these pollutants are blown into the room, potentially triggering allergies, skin irritation, and respiratory issues — especially for children and the elderly.
Water Dripping due to Drainage or Installation Issues
One of the most common reasons for leaking is blocked or misaligned drainage. When condensation water cannot flow properly, it leads to overflow or seepage.
More importantly, dripping doesn’t just damage walls, wooden furniture, and flooring — it can also become a legal issue. According to Hong Kong Law, causing nuisance by air-conditioner dripping is an offence, punishable by a fine of up to HK$25,000 plus a daily fine of HK$450.
Poor Cooling or Higher Electricity Bills
When the cooling feels weak or your bills go up, poor airflow and heat exchange are often the culprits. A dirty filter, blocked vent, or clogged condenser coil forces the unit to work harder and run longer to reach the same temperature — reducing comfort and wasting energy. The Consumer Council also recommends setting your air conditioner to 25.5°C and using a fan to improve air circulation, helping reduce energy use without sacrificing comfort.
Best Time for Air Conditioner Maintenance & Cleaning
November to January is the ideal period for preventive maintenance — when the air conditioner isn’t heavily used. A full inspection and cleaning during this time ensures your unit is ready for next summer to deliver “instant cooling” without downtime.
For professional deep cleaning, schedule it around March to May (before summer) or August to October (mid-season) — when mold activity is at its peak. Removing accumulated dust and allergens early helps maintain a clean and healthy indoor environment.
- Routine Maintenance: Focuses on cleaning the outer casing and washable filters.
- Deep Cleaning: Targets inner components such as the evaporator coil, fan blower, and air outlet.
Rotating between both methods yearly provides optimal mould prevention and energy efficiency.
3 Pro Tips for Air Conditioner Care
Humidity Control (Preventing Mould & Odors)
Humidity management is crucial — a continually damp interior encourages mold and bacterial growth. Before seasonal storage or long idle periods, switch to fan-only mode to dry out the internal parts, then turn off the power and cover the unit to prevent dust buildup and mold growth.
A common misconception: the “anti-mold” function only reduces moisture, but it does not kill bacteria or remove existing grime. It’s a preventive feature, not a substitute for proper cleaning.
Deep Cleaning (Improving Hygiene and Cooling Performance)
Deep cleaning removes hidden dirt beyond the filter — including dust that clogs the coil and reduces cooling efficiency as it involves disassembling internal parts, it’s best left to professional technicians. For households, plan one deep cleaning per year before summer, and clean the air filters 1–2 times monthly.
For a comprehensive cleaning guide, see: Air Conditioner Cleaning Guide｜How Often Should You Clean It? Full Steps and Complete Maintenance Tips
Check the Drainage Pipe Regularly (Prevent Water Leaks)
Drips from the bottom tray, the sides, or even the vent center usually indicate blockages, cracks, or installation angle issues.
If you haven’t had deep cleaning recently, arrange a cleaning plus drainage inspection. But for persistent leaks or visible water damage to walls or floors, call a professional to diagnose and repair immediately.
Want Hassle-Free Air Conditioner Care? Johnson Group Can Help!
Johnson Group Professional Air Conditioner Cleaning Team is fully trained to provide deep cleaning and sanitizing for all types of AC units.
Our eco-friendly, non-toxic cleaning solutions and advanced equipment restore cooling efficiency and remove hidden mold and dirt — ensuring a cleaner, fresher, and more energy-efficient home environment.
With over 70 years of experience serving Hong Kong households and offices, we deliver trusted expertise for long-lasting results.
Exclusive Air-Conditioner Cleaning Offer
Receive 2 bottles of SmellGREEN® Natural Cleaning Disinfectant (100ml) upon spending $2,000 on Johnson Group Air Conditioner Cleaning Service, and receive 4 bottles upon spending $3,800.
The gifts will be delivered on the day of service. Limited quotas while stock lasts!
