Aircon Chemical Wash vs Chemical Overhaul: Which Do You Need?

Aircon shops in Singapore use "chemical wash" and "chemical overhaul" almost interchangeably — which is how customers end up paying overhaul prices for what's actually a chemical wash. Here's the real difference.

Chemical wash — the on-the-wall service

A chemical wash is performed without dismantling the indoor unit. The technician:

• Removes the front cover and filters
• Sprays a chemical solution onto the visible coil + drain pan
• Catches the runoff with a plastic shield
• Wipes down the blower fan and reassembles

It's a deep cleaning — better than general servicing — but the chemical only reaches the surfaces it can spray onto. The hidden parts (back of coil, drain trap, internal fan housing) stay dirty.

Typical price: $80–$120 per unit. Time: ~45 min per unit.

Chemical overhaul — the full strip-down

A chemical overhaul is the gold standard. The technician:

• Disconnects power and refrigerant lines
• Removes the entire indoor unit from the wall
• Strips it completely apart — fan, coil, drain pan, casing
• Soaks each part in chemical solution
• Pressure washes the coil and fan
• Cleans the drain pipe end-to-end
• Reassembles, remounts, and tests

It removes every speck of grime, mould, and bacteria the unit has accumulated over the years. Typical price: $120–$140 per unit. Time: ~1.5–2 hours per unit.

At Qair we charge $120 for 9,000 / 12,000 BTU units and $140 for 18,000 / 24,000 BTU units. Same family-run pricing, no upsells.

Which do you actually need?

Chemical wash is enough when:

• Your last service was 6–12 months ago
• Cooling is slightly weaker but the unit still works
• Mild musty smell
• The unit is under 5 years old

Chemical overhaul is needed when:

• Last service was 1+ years ago (or you can't remember)
• Visible mould on the louvre or front cover
• Water dripping despite clear drainpipe
• Strong musty smell that doesn't go away
• Unit is 7+ years old and never had an overhaul
• Just bought a resale flat — no idea of service history

The honest test (try this first)

Turn the aircon on at the lowest temperature for 10 minutes. If you smell anything musty, mildewy, or "old socks" — that's mould you're breathing. No amount of general servicing or chemical wash will fully remove it from the internal housing. You need an overhaul.