Chemical Wash vs Chemical Overhaul: Which One Does Your Aircon Actually Need?

Your aircon is blowing warm air, smells a bit funky, or has started dripping onto the bedsheet at 3am. You call a technician and get the same question every Singaporean household has heard: “Chemical wash or chemical overhaul?”

The price gap between the two is big, often more than double, so it is worth understanding what you are actually paying for. This guide explains the difference in plain terms, how to tell which one your unit needs, and what to expect to pay in Singapore.

Quick answer: a chemical wash cleans the coil and fan with chemical solution while the unit stays on the wall. It is the right choice for most units that are dirty but still working. A chemical overhaul takes the whole fan coil down and soaks every part. It is for units that are heavily clogged, leaking even after servicing, or have not been cleaned properly in years. Expect roughly S$60 to S$100 per unit for a chemical wash and S$100 to S$180 per unit for an overhaul.

First, what normal servicing does (and doesn’t do)

A general service is the routine visit most households book every few months. The technician cleans the filters, wipes down the cover, flushes the drainage pipe and checks that everything is running.

It is maintenance, not a deep clean. Over time, dust, skin cells and Singapore’s humidity create a sticky layer inside the coil and on the blower wheel (the long drum fan you can see when you open the flap). General servicing can’t reach that layer properly. That is where chemical cleaning comes in.

What is a chemical wash?

In a chemical wash, the technician:

1. Covers the wall and floor below the unit.
2. Removes the cover, filters and sometimes the blower.
3. Sprays a chemical cleaning solution onto the coil (the metal fins).
4. Lets it work for a few minutes, then rinses it off with water.
5. Cleans the blower wheel and flushes the drainage pipe.

The fan coil stays mounted on the wall the whole time. It usually takes 45 minutes to an hour per unit.

Best for: units that are a year or more since their last deep clean, cool less than they used to, or have a mild smell, but are otherwise working fine.

What is a chemical overhaul?

A chemical overhaul goes much further. The technician dismantles the entire fan coil and takes it off the wall. Each part, including the coil, blower, drain pan and casing, is soaked in chemical solution, scrubbed, rinsed and reassembled.

It takes longer, often one and a half to two hours per unit. Some companies do it on site in your bathroom or service yard, while others take parts back to their workshop.

Best for: units with thick black mould on the blower, persistent leaking that general servicing hasn’t fixed, a strong musty smell, or a unit that has been neglected for several years.

Side by side

Prices are indicative ranges seen in the Singapore market. They vary by brand, unit size, accessibility (for example, units above a bed or high on the wall) and promotions.

How to tell which one your aircon needs

Use this simple checklist before your technician arrives. It helps you push back if you are upsold.

A chemical wash is probably enough if:

• Cooling is weaker than before, but the unit still gets the room cold eventually.
• There is a faint smell when you first switch on.
• The last chemical wash was about a year ago.
• The blower wheel looks grey and dusty, not black and caked.

Consider a chemical overhaul if:

• You can see black mould spots on the blower wheel or flap.
• Water keeps dripping even after general servicing.
• The unit makes rattling or squealing noises from buildup on the fan.
• It has not been deep-cleaned in three years or more, or you just moved into a resale flat and have no idea of its history.

Tip: ask the technician to show you photos of the blower and coil before and after. A good company does this without being asked. If they recommend an overhaul, ask them to show you why.

Common upsells (and how to handle them)

Most technicians are honest, but a few patterns are worth knowing.

“Your unit definitely needs an overhaul.” Ask what a chemical wash can’t fix. If the answer is vague, start with the wash.

“You need a gas top-up.” Aircon refrigerant runs in a sealed system and shouldn’t normally run low. If it genuinely is low, there may be a leak, and topping up without finding the leak is a temporary fix. Ask for the pressure reading.

Cheap headline price, expensive final bill. Some promotions only apply with a minimum number of units, or exclude units in hard-to-reach spots. Confirm the total price for your exact setup before the technician starts.

How often should you do each?

A practical schedule for units used every night:

• General servicing: every three to four months.
• Chemical wash: about once a year.
• Chemical overhaul: only when the signs above appear, which might be every few years, or never if you keep up with servicing.

Homes near construction, main roads or with pets may need more frequent cleaning because filters clog faster.

What it costs for a whole flat

Most aircon companies price per fan coil, so your total depends on how many units you have.

Many companies discount multi-unit bookings, so always ask for a package price.

Before the technician arrives

• Clear the area under each unit and move anything valuable off the bed or desk below.
• Make sure the technician can reach the outdoor condenser, especially if it is on a service ledge.
• Take a quick photo of each unit so you can compare after.
• Ask about the service warranty. Thirty to ninety days is common, which covers you if leaks return soon after.

The bottom line

For most Singapore homes, a yearly chemical wash plus regular general servicing is all you need. Save the chemical overhaul for units that are genuinely heavily soiled, leaking despite servicing, or have an unknown history. Always ask for photos, confirm the per-unit price in writing, and don’t let anyone rush you into the more expensive option without showing you why.

Looking for a trustworthy technician? See our list of the best aircon servicing companies in Singapore.

FAQs

Is a chemical overhaul better than a chemical wash?

It is more thorough, but not always necessary. If your unit is dirty but working, a chemical wash gives most of the benefit at a lower price.

Will a chemical wash fix a leaking aircon?

Often, yes, because many leaks come from a choked drainage pipe or dirty drain pan, which a chemical wash flushes. If leaking continues afterwards, an overhaul or a check on the installation gradient may be needed.

Can I use my aircon right after a chemical wash?

Usually yes. Technicians test the unit before leaving. Leave the room ventilated briefly if there is any chemical smell.

Is it safe to do a chemical wash with children or pets at home?

Reputable companies rinse the coil thoroughly. Keep children and pets out of the room during the cleaning and ask what products are used if anyone has sensitivities.