Aircon Chemical Overhaul

What is an aircon chemical overhaul?

An aircon chemical overhaul takes the indoor unit off the wall and strips it, so the coil, blower fan, drain pan and casing are chemically cleaned inside out and rinsed under high pressure. Because the refrigerant pipes are opened, the job ends with a leak check and a deep evacuation, which pumps air and moisture out of the pipes before the gas is released. We recommend it only as a last resort, for an extremely soiled aircon, because opening the pipes carries a higher risk of gas leaks.

How do we do a chemical overhaul?

1. Confirm it is needed. We open the unit first. If servicing or a wash will do the job, we say so.
2. Pump down. The refrigerant is pumped back into the outdoor unit before any pipe is disconnected.
3. Take the unit down and strip it. The casing, drain pan and blower fan come off, and the coil is separated from the body.
4. Chemical clean. Diluted coil chemical breaks down grease, dust and biofilm on every part.
5. PowerJet rinse. The jet is kept fully flat and the coil is washed from the top down, so gravity carries the dirt out and no chemical stays in the fins.
6. Reassemble and refit. The dry unit goes back on the wall and is reconnected at the flare joints.
7. Leak check. We test the joints for leaks.
8. Deep evacuation. A vacuum pump pulls the air and moisture out of the pipes.
9. Release and test. The refrigerant goes back in, and we check the gas, cooling and drainage.

Steps 7 and 8 are where cheap overhauls cut corners. Air and moisture left in the pipes can corrode the compressor and expansion valve from the inside. We explain why in is a chemical overhaul safe? and why vacuum evacuation matters.

When do you need an overhaul instead of a wash?

A wash cleans from the front and top, so dirt under the coil and between the coil and the back of the casing stays put. Only an overhaul reaches it, which is why we keep it for extremely soiled units. If the unit is clean but the room stays warm, the cause may be low gas from a leak: our gas top-up service starts by measuring the system before anything is added.

Real jobs

At The Nautical condo in Sembawang, three Mitsubishi Electric units that were not cooling were fixed with a PowerJet chemical overhaul. You can see a similar job step by step in our Starmex chemical overhaul case. In another job, a unit less than a year old smelled strongly every time it was switched on because its coil had absorbed fumes from a new wooden bed frame, and an overhaul cleared it.

What should Singapore homes know?

Most HDB flats and condos run a System 2, 3 or 4 multi-split, where several indoor units share one outdoor unit and compressor. Moisture let in while overhauling one bedroom unit can damage the whole system, which is why the evacuation is never skipped. Bedroom units that run every night in our humidity are the ones that most often reach this point.

What affects the price?

• The type of unit, such as a wall-mounted fan coil or a ceiling cassette
• Its size (BTU) and how heavy the build-up is
• Access to the indoor unit and to the outdoor unit on its ledge
• Whether the outdoor unit also needs washing, which is done only when needed and charged extra

An overhaul costs more than a wash because of the labour: taking the unit down, stripping it and rebuilding it. Each wall-mounted unit is S$180; ceiling cassettes are quoted after a S$150 on-site inspection. Every overhaul includes a free gas check and top-up (worth S$165) and a deep evacuation (worth S$395), S$560 of work at no extra cost.

Warranty

Every service includes a 90-day warranty. If a unit we serviced leaks water or stops cooling within 90 days, WhatsApp us photos or a video of the problem: the site inspection, fixing the leak and any minor repair caused by our work are free, and flare joints we remake during the overhaul are covered too. The warranty does not cover parts or installation costs, misuse, wear and tear on an ageing system, or problems from a gas leak the unit already had.