3 Must-Do's Before Turning On Your AC: Uncleaned Units Are Dirtier Than Toilets

Last week Chengdu suddenly got hot, so I turned on the AC.

Half an hour later, my nose started itching, followed by a series of sneezes.

Thought it was pollen allergies, then realized—wait, I’m indoors, where’s the pollen?

Then it hit me: this AC hasn’t been cleaned since winter shutdown—four or five months.

Opened the filter panel and nearly vomited.

That layer of dust, lint, invisible bacteria and mold… I’d been breathing this for 30 minutes?

Did some research—utterly shocked.

Data shows one-year-old AC filters can harbor thousands of bacteria per square centimeter. Three years uncleaned? Hundreds of thousands.

What does that mean? Dirtier than a toilet.

Not exaggerating—CCTV ran special reports. News about AC-induced pneumonia and asthma appears every summer.

So this year, I got serious about ‘AC cleaning.’

Did lots of homework, summarized three essential pre-summer steps.

First, wash the filter.

Most basic, everyone can DIY.

Turn off power, open panel, pull out filter. You’ll see grayish-white fluffy stuff—dust, skin flakes, fiber mixture.

Gently brush surface dust with soft brush, then soak in neutral detergent (dish soap works) diluted in warm water for 15 minutes.

Note: no hot water, no strong acid/alkaline cleaners—damages filter material.

Rinse clean, air dry. Note: air dry, no direct sun—filter deforms easily.

Second, clean the evaporator.

The dense metal fins behind the filter—that’s the evaporator. Core cooling component, easiest place for dirt accumulation.

Evaporator gaps are narrow; regular cloths can’t reach. I bought specialized AC cleaner—spray, wait 10 minutes, foam lifts dust and bacteria out.

Then gently brush with soft brush following fin direction. Don’t brush against grain—bends fins.

Do this at least annually. High usage or homes with elderly/kids? Quarterly is better.

Third, check the drain pipe.

Many overlook this, but clogged drains cause AC leaks.

Find outdoor unit drain outlet, check for blockages. If possible, use thin wire or specialized tools to clear.

I also pour diluted disinfectant down drain pipes to kill bacteria and algae.

After these three steps, your AC is basically ‘like new.’

But that’s not all.

Some daily usage tips.

First, don’t set temperature too low. Large indoor-outdoor temperature differences strain the body. I set 26°C—comfortable and energy-efficient.

Second, don’t run continuously. Every 2-3 hours, turn off and ventilate 15 minutes. Fresh air lowers indoor CO2 and bacteria concentration.

Also, use ‘sleep mode’ or timer at night. Temperatures drop naturally overnight—continuous blowing risks colds.

Sounds like a lot of trouble?

I calculated time costs:

Filter washing: 20 minutes.
Evaporator cleaning: 30 minutes.
Drain check: 10 minutes.

About an hour total, once or twice yearly.

Skip it, potential costs: medical bills, medication suffering, constant nasal congestion discomfort.

Worth it, in my book.

Of course, if you’re truly lazy, hire professional cleaners. Market rate: 100-200 yuan per wall unit.

But I suggest at least learning to wash filters yourself. Simplest maintenance, most direct results.

One final detail.

After reassembling, before first night’s use, I opened windows and ran ‘fan mode’ for 30 minutes.

Disperses residual cleaner smells, lets internal moisture evaporate.

That night’s sleep—noticeably fresher air. No more ‘AC smell,’ just clean, crisp breeze.

Summer is AC heavy-use season. Prep time now means comfort all season.

Don’t wait until problems arise—too late then.

Has your AC been cleaned?