Convert Any Fan Into a Free Air Conditioner (That Actually Works)

I found most of this stuff lying around the house. So for me, this was a free air conditioner. And yeah, I tested it — it actually dropped the room temperature by a couple of degrees. But there’s a catch: water and electricity don’t mix, and frozen bottles sweat like crazy. You need to be smart about it.

This came about because there’s a heatwave moving through Europe and the UK right now. In France, stores ran out of air conditioning units. People were fighting over them. If you can’t buy one, or don’t want to spend the money, this hack works — if you do it right.

• A tabletop fan (mine was about £15)
• Plastic water bottles (500ml or 600ml work well)
• Salt (1-2 tbsp per 500ml bottle)
• Hair ties, zip ties, paper clips, carabiners, or anything you can use to attach bottles to the fan grill
• A towel (to wipe condensation)
• An RCD (residual current device) for electrical protection – seriously, use one
• Optional: a tray to catch drips

1. Prepare the Bottles

Fill your bottles with water, but leave space at the top — ice expands. For a 500ml bottle, add about 1-2 tablespoons of salt before freezing. The salt lowers the freezing point so the ice stays colder longer and doesn’t freeze into a solid block. Too much salt and it won’t freeze properly — you get slush.

Freeze them solid.

When you take them out, they look dry at first. But within a few minutes, condensation forms. That’s the water that can drip into your fan motor, plug, or extension cord. Wipe each bottle down with a dry towel before attaching.

2. Attaching Bottles to the Fan (Several Methods)

The goal is to hold the bottles securely behind the fan grill (or in front) without blocking the air intake. Fans need airflow — block the intake and the motor overheats.

Method 1: Hair tie + paper clip

Take a hair tie and wrap it tightly around the neck of the bottle. Twist it a few times so it’s snug. Then unfold a paper clip and hook it under the hair tie. Use the paper clip to attach the bottle to the fan grill. Do this for both bottles, one on each side of the back. Don’t block the center of the fan — that’s where air comes in.

Method 2: Zip ties

Zip ties work great. If you need extra length, push the end of one zip tie into the head of another — you get double the length. Wrap a zip tie around the bottle neck, pull it tight, and then hook it onto the fan cage. For extra stability, add a second zip tie lower down so the bottle sits closer to the fan.

Method 3: Ice packs with zip ties + picture frame hooks

Ice packs are wider. Use two zip ties joined together to wrap around the pack lengthwise. Then do another pair around the width. Attach a picture frame hook (or a bent paper clip) to the top zip tie, then hang the pack from the fan grill. Keep the pack right-side-up so any melting water stays inside.

Method 4: Carabiners, padlocks, pegboard clips

Anything that can clamp around the bottle neck and clip onto the fan works. I used a padlock because the shackle fit perfectly through a zip tie loop and hooked onto the grill. Get creative with what you have.

3. Secure Everything

Once bottles are attached, make sure the fan can’t oscillate. Most fans have a button or switch to lock it in place. Turn that on — otherwise the swinging motion will throw the bottles off.

4. Position the Fan

Set the fan on a stable surface. Keep the plug and extension cord off the floor in case of drips. I put a small wooden block under the front of my fan because the weight of the bottles made it tip forward. A wedge or a book works.

Room temperature was 23.6°C when I started. I turned the fan on high. The air coming out felt noticeably colder than a normal fan — the bottles behind the fan cool the air being sucked in, and the bottles in front cool the air being blown out.

After running for a while, the temperature dropped to 21°C. That’s a real 2.6°C difference. For a few frozen bottles and a cheap fan, that’s impressive.

The cooling effect lasts about 1-3 hours. The bottles stay frozen for 3-6 hours depending on room temperature.

Condensation will drip. Even if your bottles don’t leak, water forms on the outside and drips down. I saw water on the table within minutes.

• Never leave this running unattended.
• Don’t use it overnight while you sleep.
• Use an RCD plug – it cuts power if there’s a fault.
• Keep all electrical connections away from the floor.
• Wipe bottles dry before attaching, and periodically check for drips.

The safest way to do this, in my opinion: put a tray in front of the fan and place your frozen bottles in the tray (standing up, lids on). The air blows over the cold bottles and you get the same cooling effect without risking water getting into the fan motor.

• Don’t block the fan intake. The motor needs airflow to stay cool.
• Use fabric hair ties or string instead of rubber bands – rubber bands slip off and snap.
• If the fan starts tipping from the weight, prop it up or use smaller bottles.
• Salted ice melts at a lower temperature, so it stays colder longer, but it also sweats more. Test with unsalted bottles first if you’re worried about moisture.

This hack works. It’s cheap, it’s fast, and it uses stuff you already have. But water + electricity is a bad combination, so treat it with respect. If you’re careful, you get a few hours of real cooling. If you’re not careful, you get a fire risk.

Personally, I’d rather buy a proper air conditioner if I can. But if you can’t find one or can’t afford one, this will get you through a heatwave.