Blog Maintenance
Aircond Overhaul vs Chemical Service: Differences, Price and Which You Need
A chemical service deep-cleans the coil with the unit on the wall. An overhaul takes the indoor unit down and strips it apart. Here's how to tell which one your aircond actually needs.
Short answer: a chemical service deep-cleans the cooling coil and blower while the indoor unit stays on the wall. An overhaul takes the indoor unit off the wall and strips it down so every part can be washed. Most regularly serviced home units only need a chemical service once a year. An overhaul is for units that have been neglected for a long time, smell bad even after cleaning, or keep leaking water.
People use these words loosely, and some shops use them to upsell. Here's what each one really involves, so you can tell whether you're being quoted the right job.
Normal service vs chemical service vs overhaul at a glance
| Normal service | Chemical service | Overhaul | |
|---|---|---|---|
| Indoor unit stays on the wall? | Yes | Yes | No, taken down and stripped |
| What gets cleaned | Filter, fins, casing, drain flush | Coil and blower washed with coil cleaner, drain cleaned | Every part washed separately: coil, blower wheel, water tray, casing, plus outdoor condenser |
| Typical time per wall unit | 30 to 45 minutes | 60 to 90 minutes | The longest of the three, usually a couple of hours |
| Best for | Units serviced every 3 to 4 months | Cooling and airflow have dropped, musty smell | Long-neglected units, mould, slime, repeat leaks |
| Marvel price, wall unit | RM88 (RM68 each for 3+) | RM198 (RM148 each for 3+) | Quoted on inspection |
You may also hear "chemical wash" (same as chemical service) and "chemical overhaul" (same as overhaul). The names change from shop to shop; what matters is whether the unit comes off the wall.
What happens in a chemical service
A chemical service is the deep clean most units need once a year in KL conditions:
- Power off and cover the wall and floor
- Remove the filters and front panel
- Fit a waterproof service bag around the indoor unit
- Spray coil cleaner onto the cooling coil and let it work into the fins
- Rinse the coil and the blower wheel with a pressure pump until the water runs clear
- Clean and flush the drainage line
- Check gas pressure and run a cooling test
Because the unit stays on the wall, it's quicker and cheaper. The limitation is reach: the back of the blower wheel and the inside of the water tray can only be cleaned so far without taking the unit apart.
What happens in an overhaul
An overhaul goes further, because the indoor unit is taken down:
- Power off, then safely detach the indoor unit from its wall bracket
- Strip it down: casing, louvres, water tray, blower wheel and motor cover
- Wash each part separately, including the inside of the water tray where slime builds up
- Chemical-wash the coil from both sides
- Clean the outdoor condenser coil and fan
- Flush the drain pipe end to end
- Reassemble, remount at the correct drainage slope, check gas pressure and test cooling
This is the only way to get rid of thick black mould on the blower wheel, slime in the water tray, or a smell that comes straight back after a normal clean.
Signs your aircond needs an overhaul, not just a chemical service
- It hasn't been cleaned properly for two years or more
- You can see black spots or slime on the blower wheel through the louvres
- Black specks blow out when the aircond starts
- A musty or sour smell comes back within weeks of a service
- Water keeps dripping from the front even after the drain was flushed
- Cooling is still weak after a chemical service, and the gas pressure is fine
If only one or two of these apply and the unit was serviced within the last year, a chemical service usually does the job. We check on site and tell you which one it needs. We won't push an overhaul when a chemical service will do.
When neither will fix it
Cleaning fixes problems caused by dirt. It won't fix a gas leak, a failed capacitor, a faulty fan motor or a sensor fault. If the outdoor unit isn't running, the unit trips the breaker, or the pipes ice up, that's a repair job. Our guide to why an aircond is not cold walks through those causes.
How much does an aircond overhaul cost?
We quote overhauls on inspection because the work varies a lot. A 1HP wall unit in an easy-to-reach bedroom is a very different job from a ceiling cassette or a ducted unit, or a unit so clogged that every part needs soaking. WhatsApp us a photo of the unit (and the blower wheel if you can see it) and we'll give you an indicative price before we come.
For reference, our chemical service is RM198 for one wall unit, RM178 each for two, and RM148 each for three or more. Full price tables for cassette, ceiling exposed and ducted units are on our aircond service page.
Frequently asked questions
How often does an aircond need an overhaul?
A well-maintained home unit rarely needs one. If you do a normal service every 3 to 4 months and a chemical service once a year, the unit stays clean enough that an overhaul isn't necessary. Overhauls are mainly a reset for units that missed years of servicing. See how often to service your aircond.
Is an overhaul risky for an old unit?
Taking a unit down puts some stress on the copper pipe joints, which is why it needs an experienced technician who checks the pipes and gas pressure after remounting. On very old units, we tell you upfront if the pipes or casing look fragile, so you can decide whether an overhaul or a replacement makes more sense.
Will a chemical service lower my electricity bill?
Usually, yes. A clogged coil makes the compressor run longer to reach the set temperature. Cleaning restores airflow and heat transfer, so a neglected unit typically draws less power after a proper clean.
Can I chemical wash my aircond myself?
We don't recommend it. Coil cleaners are strong chemicals, the indoor unit has live electronics close to the coil, and water in the wrong place can damage the circuit board. Cleaning the filter yourself every few weeks is great; leave the coil to a technician.
Not sure which one you need?
WhatsApp Marvel a photo or short video of your indoor unit and tell us when it was last serviced. We'll tell you honestly whether it needs a normal service, a chemical service or an overhaul, and confirm the price before anyone arrives.