Before Turning on the AC This Summer, Most People Skip This Step

Last week in Chengdu, the temperature suddenly shot up to 30 degrees. The first thing I did when I got home was turn on the air conditioner.

And that smell… how should I put it, it was like the “warm” musty smell of a quilt that had been stored all winter under the hot sun.

My first reaction was: is the AC broken? Should I call for repairs?

Later, calming down: wait, before the last summer ended, I don’t think I did any cleaning maintenance.

As expected, after some research I found—many AC problems are actually caused by “not cleaning before turning it on.”

The Must-Do List Before Starting Your AC

Here’s the checklist I compiled after 3 nights of research:

1. Filter Cleaning (Most Important)

Everyone knows about this, but what I want to say is: most people don’t clean thoroughly enough.

Correct approach:

• First use a vacuum cleaner to suck up surface dust on the filter
• Then soak in warm water with a small amount of neutral detergent for 15 minutes
• Gently brush with a soft brush, being careful not to damage the filter with too much force
• Let dry completely before reinstalling (must be fully dry)

When I cleaned my filter last time, I just rinsed it with water and reinstalled it right away. Thinking about it now, that “almost dry” might have been one source of my AC odor.

2. Radiator Cleaning (What Many People Miss)

The radiator behind the filter is the real “disaster area.”

Because of its structure, dust and bacteria accumulate in the gaps. Cleaning the filter alone isn’t enough.

My approach:

• Bought a special AC radiator cleaning spray
• Removed the filter first, then evenly sprayed the radiator with the cleaner
• Waited 15 minutes, letting the cleaner fully break down the grime
• Finally gently wiped with a damp cloth (don’t use a too-wet cloth)

Note: don’t use a pressure washer or flood with large amounts of water. The radiator is delicate, and water ingress can damage it.

3. Air Outlets and Guide Vanes

These areas also accumulate dust easily, but cleaning frequency can be lower than the filter.

My experience: wipe them down every time you clean the filter, no need for deep cleaning every single time.

4. Indoor Unit Shell

Wipe with a slightly damp cloth. Focus on the rubber sealing strip around the air outlet—this is where mold loves to hide.

A Simple Method to Judge Whether Your AC Needs Cleaning

No professional equipment needed—just a phone flashlight:

Open the AC panel, remove the filter, then shine the flashlight from different angles toward the radiator. If you see a dusty gray layer on the radiator, it needs cleaning.

If the radiator looks relatively clean but the AC has an odor when running, it’s probably a clogged drain pipe or water accumulation in the collecting pan—in this case, suggest calling a professional.

After Cleaning, Don’t Rush to Max Mode

Many people, after cleaning the AC, can’t wait to set the temperature to the lowest and fan to the highest.

My advice: first run for half an hour in ventilation mode (or just fan mode), letting internal moisture fully evaporate, then switch to cooling mode.

This prevents residual moisture from causing mold inside the machine.

My AC now has zero odor. Above are all my insights from 3 nights of research.

Sisters, listen to me: before turning on the AC for the first time in summer, do these steps first. Don’t be like me, waiting until you smell something before feeling regret.

After all, the AC is for staying cool, not for smelling.