Many of us wouldn’t survive a week without air-conditioning, but our favourite home appliance may be more dangerous than we think. By Simon Stanley. Photo by Vinh Dao.

Talk about coincidences… I’d just sat down to write this piece – my own AC blowing warm air as it often does – when I heard a dripping sound coming from the balcony where our three compressor units live.

It wasn’t the sound of dripping water, but of dripping, red hot plastic. One of the units was on fire. By the time I’d alerted someone, grabbed a fire extinguisher and returned, smoke was pouring into the sky and flames had engulfed the balcony. Emptying the entire canister onto the fire, the scene (and I) disappeared behind a white cloud of carbon dioxide. The fire was out and I’d escaped with only a few minor burns from the gloopy plastic now spattered everywhere.

The culprit? A short-circuit in the compressor’s starter switch, a very freak occurrence apparently. Such incidents serve as reminders to always turn off the AC when leaving the house and, in the long-term, to ensure our systems are well maintained (often a difficult task in a country where trained, certified technicians are practically non-existent). While fires are extremely rare, air-conditioning poses a number of potential health risks. Here are five issues to be aware of:

1 – Keep it Clean
Does your AC air smell like dirty socks? Maybe it’s no longer cooling the room sufficiently and instead puffing damp, musty air. A dirty system may be the problem. Firstly, according to Tomoki Miyamoto, Panasonic’s air-conditioning general manager, the air-filter inside the internal evaporator unit should be cleaned every two weeks. This is normally a screen of microfine mesh that can be accessed via the front panel, removed and washed in warm soapy water. “The evaporator is very humid,” explains Miyamoto, “therefore the risk of mould and bacteria growth will be higher.”

The evaporator itself should also be cleaned at least once a year. Special sprays, widely available abroad, may be hard to find in Saigon, but speak to your local handyman or woman (or the customer service department for your particular brand), about getting it cleansed. For ducted AC systems, with long, inaccessible air-channels, the risk of harmful micro-organisms forming is even higher. Once airborne, they can cause sickness and potentially fatal respiratory infections such as pneumonia and Legionnaire’s disease.

Many modern AC units feature built-in cleaning functions. Panasonic’s nanoe-G system is one of them. “It’s an ioniser,” says Miyamoto, “able to purify airborne and adhesive objects. It also deactivates viruses and mould by up to 99 percent.”

Cleaning the waste water pipes annually is also recommended. As moisture in the warm air condenses on the cold fins of the evaporator (like the sides of a glass of iced tea) the fluid drains into a gutter and runs outside. If your evaporator unit begins to leak, this drain may be blocked with dirt, fluff and other nasties.

2 – Let it Breathe
While you should keep windows closed while the AC is on, most small-scale residential systems are ‘sealed’, recycling the ‘old’ air rather than bringing in fresh air from outside. If airborne pollutants such as germs, mould, dust and bacteria are present, they may never leave. Bedrooms are the primary culprits. Miyamoto suggests that a ventilation fan, installed higher than the AC unit, is the best solution. “In cases where this is not possible,” he says, “you should leave the door open around one to two centimetres.”

In the case of ducted AC, in a room without a ‘return’ vent and with the door closed, the increased air pressure can also lead to respiratory problems, poor sleep and feelings of overall discomfort.

3 – Avoid Direct Airflow
The dehumidifying effect of the AC process dries out mucus membranes in the sinuses, thus causing irritation and reduced protection against colds, flu and other illnesses. Miyamoto raises the added issue of skin dryness. “To avoid it,” he says, “it is recommended to cool the room while avoiding direct airflow to yourself. Panasonic has just introduced a new AC series named ‘Sky’, with a radiant cooling function which has been proven to prevent skin dryness.”

If you’re stuck in a home or office with AC, stay hydrated, look after your skin, keep out of the draught and try to get ‘fresh’ air regularly.

4 – Not Too Cold
Headaches, coughs, sore joints, fatigue, painful sinuses and an exacerbation of existing health conditions such as low blood pressure and arthritis have all been linked to the icy blasts of overzealous air-conditioning.

Setting the thermostat too low at night can also lead to poor sleep quality and a weakened immune system. 18C (65F) is the sweet spot most sleep researchers point to, but as we all know, rarely does an AC’s thermostat match the actual temperature of a room. The ‘breezy’ nature of AC can also make temperatures deceivingly low. Consider using a normal fan at the same time.

Your AC unit may offer a sleep-mode, often symbolised by a sleeping face or a moon. This normally means a preset temperature and fan setting best suited for nighttime use.

For cooler days (and nights), consider using the drying mode (normally shown with a water droplet symbol). This removes moisture from the air without cooling it as humidity can make otherwise comfortable temperatures unbearable.

5 – Leaky Pipes
Another common AC fault is a leaky gas line. If your system is blowing warm air, it may need to be re-gassed. In Vietnam, most building maintenance personnel will be familiar with this. The gas is relatively odourless and only harmful if long-term exposure occurs, but do open doors and windows if you suspect a leak. While most systems will need topping up from time to time, like a bike tyre, if it happens every week it’s time to investigate. 

1. A special type of gas, known as a refrigerant, is compressed to form a liquid. This gives off heat, hence the need for an external, fan-cooled compressor.

2. The liquid then moves indoors to the evaporator. In many homes, shops, offices and restaurants, this is the large rectangular unit hanging high up on the wall. For ducted AC, the evaporator will be hidden out of sight.

3. Once inside the coiled pipes of the evaporator, the pressure is released and the refrigerant turns into a gas again.

4. This process absorbs heat from the surrounding air, thus cooling it. Aided by a fan and a rack of metal fins (much like a car’s radiator working in reverse), the cooled air is blown into the room.

5. The gas then returns to the compressor for the process to begin again.