An aircon chemical overhaul costs more than a chemical wash, and from the outside the two look almost the same. A technician arrives, covers the floor, runs some water, sprays something, and leaves a unit that smells fresh and blows cold. Cold air and a fresh smell are what you would get from a wash too, and a wash is cheaper. So the fair question after you have paid for an overhaul is: how do I know the unit was actually taken apart?
This guide is for the person who has booked an overhaul, or is about to. It sets out what the job is supposed to include, what you can check on the day without any technical knowledge, how the time and the price give the game away, and what to do if the answer is "not much". Every figure is from our published price tables and service pages. Where a number is our own arithmetic, we say so.
What an overhaul is supposed to include
Our chemical overhaul page describes the job as a full strip-down of the indoor fan coil unit. The blower, the drain tray, the casing and the covers are removed, and each part is cleaned individually with specialised chemicals. The steps it lists are:
- The 9-point pre-check, to confirm an overhaul is genuinely needed.
- Full disassembly of the indoor fan coil unit.
- Individual chemical cleaning of every component, with an anti-bacterial treatment on the coil.
- The blower wheel cleaned and balanced.
- The circuit board inspected and dust-cleared.
- Anti-rust coating on the metal components.
- The drain tray and pipe pressure-cleaned.
- Full reassembly and a 5-point performance test before the technician leaves.
One detail that surprises people: the unit is dismantled in place. Our overhaul page says the covers, blower and drain tray come off for individual cleaning without taking the whole casing off the wall. So do not expect to see the unit carried out of the room. What you can expect to see is parts coming out of it.
What a wash does instead
A chemical wash cleans the evaporator coil and the drainage without taking the unit apart. That is a legitimate job and the right one for most units on a 6 to 12 month rhythm. It is also quicker and cheaper. The trouble starts only when a wash is sold or labelled as an overhaul. Our chemical wash page and the overhaul page both say the same thing: a wash cannot physically reach the blower wheel, the inside of the casing or the board, which is exactly where an overhaul is meant to work.
Check 1: the clock
This is the easiest check because you do not need to look at anything. Our published time is about 2 to 3 hours per indoor unit for an overhaul, because each part is removed and cleaned on its own. A chemical wash is 60 to 90 minutes per unit, and a general service is 30 to 45 minutes.
The overhaul page says a full 3-unit HDB flat is usually a half to full day, depending on access and the condition of the units. A chemical wash on the same three units is well under half a day. So if three units were "overhauled" and the technician was gone in an hour or two, the time was a general service or a wash, not an overhaul. Time on site is not proof of quality, but time that is far too short is proof that the job was not the one you paid for.
Check 2: ask to see the blower wheel out
The blower wheel is the long cylinder behind the front grille that moves the air. It is the part an overhaul exists to reach, and it is the part a wash leaves in place. Ask on arrival, not at the end, to see it once it is out and cleaned. Ask the same for the drain tray. A technician doing a real overhaul has had both out of the unit at some point in the job, so this is not a favour. A technician who has not taken them out has nothing to show you.
Our article on what your aircon technician should show you before they leave goes through the blower wheel, drain pan, filters and coil face for any service. For an overhaul, the first two are the ones that count.
Check 3: the covers are off, not sprayed through
An overhaul needs the covers and casing removed. Spraying solution through the front grille is not an overhaul, and it is not a proper wash either. We say the same about washes in what a cheap chemical wash leaves out. If you walk in and the unit is still fully assembled halfway through the job, ask what is being done.
Check 4: before and after photographs
Ask for a photo of the blower wheel and the inside of the casing before cleaning and again after. It takes seconds, it costs nothing, and it changes how the job is done. It also settles the argument three months later, if the smell returns, about whether the part was actually cleaned. If a technician is reluctant to photograph the work, that is useful information on its own.
Check 5: what did you find on the board?
An overhaul includes inspecting the circuit board and clearing the dust from it. You cannot judge that yourself, but you can ask: "what did you find?" A real answer names a unit and a condition, for example "the living room board had dust build-up, the bedroom one was clean". A vague "all okay" tells you nothing. If something else is found, such as low gas or a worn part, our rule is that it is quoted before any work is done on it. You should be given the price first, not told afterwards.
Check 6: the test before they leave
The last step on our list is a 5-point performance test after reassembly. You should see each unit switched on and running before the technician packs up, ideally for long enough to hear it at switch-on and when the fan changes speed. A technician who refits the covers and walks out has not confirmed anything. If you want to know what to look for in the days that follow, we cover it in what is normal after an overhaul and what goes back to the technician.
The price check: overhaul versus wash
Our published tables make the gap between the two jobs clear, so a quote that sits on top of the wash figure is a warning. Here are the two side by side, with the difference worked out.
| Indoor units | Chemical wash | Chemical overhaul | Difference |
|---|---|---|---|
| 1 | $135 | $200 | $65 |
| 2 | $245 | $370 | $125 |
| 3 | $345 | $515 | $170 |
| 4 | $425 | $640 | $215 |
| 5 or more | $100 per unit | $150 per unit | $50 per unit |
The "Difference" column is our subtraction of the two published prices. The reading we draw from it is an inference, not a rule: if you were charged an "overhaul" price at or below the wash price for your number of units, ask what is on the invoice. For a real overhaul to be priced at a wash price, the time and labour would have to be missing from it. Compare other companies on your number of units, not on a "from" headline. Our wash page says "from $100", and that rate starts at the fifth unit. The same trap applies to overhaul headlines.
What to ask before you book
- What is the price for my number of units, and is it final?
- Does the job include taking out the blower wheel and the drain tray, and can I see them?
- Are the covers and casing removed, or is it cleaned through the grille?
- Will you take before and after photos?
- How long will each unit take? (Our published figure is 2 to 3 hours per indoor unit.)
- Is there a check first to confirm an overhaul is needed, and will I be quoted anything extra before it is done?
Our own answers, from the overhaul page: the price is the one on the table, it is final, and the 9-point pre-check comes with every service booking ($45 minimum for one unit). If the pre-check turns up a separate problem, we quote it before doing anything. We will not strip a unit that only needs a wash.
What you cannot use as proof
- Cold air. A unit with a fouled blower wheel still blows cold on the day.
- A fresh smell. A wash gives you that too.
- Wet floors and a lot of water. Water is used in both jobs.
- A tidy unit. A cover wiped down looks clean from the front.
The honest test comes later. A musty smell or weak cooling that returns soon after the work is, on our overhaul page's own list, one of the signs a unit needs an overhaul in the first place. If it returns soon after a job that was sold to you as an overhaul, go back to the company that did it, with the photos, and ask what was cleaned.
If you did not need an overhaul at all
Sometimes the real problem is that the wrong job was sold. Our overhaul page lists when an overhaul is the right call: the smell or weak cooling came back soon after a wash, the unit is more than 5 years old and has never been overhauled, heavy mould or grime is visible on the blower wheel or inside the casing, cooling has dropped and a wash made little difference, or water keeps overflowing despite drain cleaning. If none of those apply, a wash, or even a general service, may have been enough. For units under about 8 years old and in sound mechanical condition, our page says an overhaul restores most of the original cooling and airflow. Older units, or those with a tired compressor, improve clearly but may not fully recover. If the unit is near the end of its life, replacing it can be the smarter spend, and overhaul or replace: how to decide covers that.
The short version
An overhaul should leave you with parts you saw come out, a time on site of roughly 2 to 3 hours for every indoor unit, a price that sits above the wash price for your number of units, and a test before the technician leaves. If the visit was 30 to 90 minutes per unit, the covers never came off, and nobody can show you the blower wheel, you paid for a wash or a service. Ask the questions above before you book, and take the photos on the day.
Full prices for every job are on our pricing page, and the job itself is described on the chemical overhaul page.
Not sure whether your unit needs an overhaul or just a wash? WhatsApp us on 9107 2601 with your number of units and what the unit is doing, and we will tell you which job it needs before anyone comes out.