Chemical Wash vs Chemical Overhaul: Which Does Your Aircond Need?

Understanding the Difference Between Chemical Wash and Chemical Overhaul

You likely know the struggle of a warm night in Petaling Jaya when the AC just won’t get cold enough.

We hear the same question almost every day from homeowners facing this issue.

Is a standard chemical wash enough to fix it, or does the unit need a full chemical overhaul?

These terms often get used interchangeably, but they refer to completely different procedures with distinct price tags.

PJ Kool Aircond Service performs both jobs daily across the Klang Valley, so we have seen exactly what happens inside these machines.

This guide breaks down the specific technical differences, the costs involved, and how to spot which service your unit actually requires.

What Is an Aircond Chemical Wash?

A chemical wash is a maintenance procedure designed to clean the unit without removing it from your wall.

Our technicians focus on the components that are accessible from the front and bottom of the indoor unit.

This process targets surface-level grime and bacterial buildup that restricts airflow.

We remove the front cover, filters, and casing to expose the evaporator coil.

A specific chemical solution is then applied to the coil and blower to dissolve the “jelly” (biofilm) that accumulates in our humid Malaysian climate.

The Specific Steps Involved

• Coil Saturation: We spray an alkaline-based chemical onto the evaporator fins to foam out trapped dust.
• Blower Cleaning: The fan roller gets brushed and rinsed to remove the heavy dust layer on the blades.
• Drainage Flushing: Water is forced through the drainage pipe to clear minor blockages.
• Filter Restoration: The mesh filters are deep-cleaned to remove impacted dust.

Time Required

Expect the process to take 45 to 60 minutes per unit.

Cost in Petaling Jaya

Market rates currently sit between RM80 and RM150 per unit.

Prices vary based on the horsepower (HP) of your wall unit or cassette.

What Is an Aircond Chemical Overhaul?

A chemical overhaul is a “major surgery” for your air conditioner.

This procedure requires the complete dismantling of the indoor unit from the wall bracket.

We take the unit down and disassemble every single part to clean them individually.

It is the only way to reach the back of the evaporator coil and the inner crevices of the drainage tray where mould thrives.

This service is necessary when the grime has become so compacted that water pressure alone cannot dislodge it.

The Overhaul Protocol

• Total Dismantling: We pump down the refrigerant gas (pump down) and remove the entire indoor unit from the wall.
• Component Separation: The PCB (motherboard), motor, blower, and evaporator coil are separated.
• Chemical Bath: Waterproof parts are soaked in a chemical tank to strip away oxidation and hardened gunk.
• Heat Exchange Cleaning: The coil is washed from both the front and back to restore full thermal transfer efficiency.
• Re-installation & Vacuum: We mount the unit back up, vacuum the copper pipes to remove moisture, and release the gas.

Time Required

This intensive process takes approximately 2 to 3 hours per unit.

Cost in Petaling Jaya

You should budget between RM180 and RM350 per unit.

The higher cost reflects the labour intensity and the technical risk involved in dismantling the electronics.

Side-by-Side Comparison

Making the right choice comes down to knowing exactly what you are paying for.

Feature	Chemical Wash	Chemical Overhaul
Unit Status	Remains on the wall	Completely removed from wall
Cleaning Depth	Front surface & accessible parts	100% deep internal clean
Drainage	Pipe flushed with water	Tray & pipe chemically treated
Components	Cleaned in-situ	Separated & soaked individually
Gas Handling	Not involved (usually)	Pump down & vacuum required
Time Per Unit	45-60 minutes	2-3 hours
PJ Market Rate	RM80 - RM150	RM180 - RM350
Best Frequency	Every 6-12 months	Every 2-3 years

When Should You Choose a Chemical Wash?

A standard chemical wash is usually sufficient for units that have been serviced within the last 12 months.

We recommend this service if you want to maintain efficiency without the risks associated with dismantling the unit.

Opt for a chemical wash if:

• Routine Timeline: It has been 6 to 12 months since your last professional cleaning.
• Mild Odours: You notice a slight musty smell when the unit first turns on.
• Airflow Drop: The wind strength is slightly weaker than usual but the room still cools down eventually.
• Visible Dust: You can see dust on the filters, but the flashlight test shows the inner blower wheel is still relatively clean.
• Budget Control: You need an effective clean for RM100-RM150 rather than a pricier overhaul.

Think of this as a deep clean for your car.

It removes the dirt you can see and improves performance, but it doesn’t involve taking the engine apart.

When Should You Choose a Chemical Overhaul?

An overhaul becomes necessary when a unit has been neglected or is showing signs of severe blockage.

Our team often finds that standard washing cannot penetrate the thick layers of grime on older units.

An overhaul is required if:

• Severe Neglect: The unit has not been serviced for 2 years or more.
• Water Leaks: You have a persistent water drip that a general servicing didn’t fix (this indicates a jelly blockage in the back tray).
• Weak Cooling: The air coming out is not cold even when the setting is at 16°C.
• The “Jelly” Factor: You see thick, slimy substance (biofilm) on the cooling fins.
• Fan Blockage: The blower wheel is so caked with dust that you cannot see the individual blades.
• Noise Issues: The unit makes rattling or grinding sounds caused by an unbalanced, dirty fan.

This process is effectively a factory reset.

We clear out 99% of the contaminants that a standard wash simply cannot reach.

Common Misconceptions

There is a lot of bad advice floating around regarding aircond maintenance in Malaysia.

Let’s clear up a few myths that could cost you money or damage your machine.

”A chemical overhaul is always better”

More is not always better.

Frequent dismantling loosens the plastic clips and screws that hold your unit together.

We have seen casings rattle permanently because they were taken apart too many times.

Save the overhaul for when it is genuinely needed (every 2-3 years) and stick to chemical washing for regular maintenance.

”Chemical washing destroys the coil”

This is only true if the wrong chemicals are used.

Some inexperienced technicians use harsh acidic cleaners (often pink or red liquids) that eat away the protective blue fin coating on the copper coils.

Our team uses alkaline-based solutions that are safe for aluminium and copper components when rinsed properly.

Always ask your technician what type of chemical they are using.

”I need a gas top-up with every wash”

This is the most common scam in the industry.

Air conditioners run on a closed-loop system, meaning they do not consume gas like a car consumes petrol.

Unless there is a leak, your gas level should remain constant for years.

If a technician insists on topping up gas every time, ask them to show you the leak first.

Our Recommendation

The right choice depends entirely on the current health of your unit.

PJ Kool Aircond Service always begins with a physical inspection before recommending a path forward.

We advise a simple maintenance rotation to keep your electricity bills low and your air clean.

The Ideal Maintenance Cycle:

1. Year 1: Chemical Wash at Month 12.
2. Year 2: Chemical Wash at Month 12.
3. Year 3: Chemical Overhaul at Month 12 (to reset the system).

This schedule prevents the heavy buildup that kills compressors while avoiding the wear and tear of unnecessary dismantling.

If you aren’t sure which category your unit falls into, check the blower wheel with a torchlight or give us a call.

We cover all areas in Petaling Jaya, Subang Jaya, Shah Alam, and KL.

Let’s get that cold air flowing again without wasting money on services you don’t need.