Keep haze out of the car with Recirculate mode and change air-conditioning filter regularly

Do I need to take any special precautions or make any upgrades to my car’s ventilation system in response to increased haze levels?

If you have been diligent in maintaining your car’s air-conditioning system, then all you need to bear in mind are just a couple of non-routine measures to maintain a healthy environment inside your car when the air pollution index begins to creep up.

First, you need to monitor the status of the recirculation mode more closely. Under regular conditions, it is good practice to periodically allow fresh air into the cabin. However, when the haze is noticeable, keep the Recirculate mode activated, especially in stop-go traffic, to minimise ingress of outside air.

Note that prolonged recirculation, such as on drives that last more than 45 minutes or so, is not recommended. The oxygen level drops gradually and cabin conditions could end up being worse than the haze outside.

Second, you will need to have the air-con filter replaced more frequently during haze seasons because particulate build-up will definitely increase.

On the other hand, if you have not been regularly servicing the car’s air-con system, here are a few tips.

Even if your car’s handbook does not specify the service interval for air-conditioning, it is a good idea to practise a periodic maintenance routine.

In Singapore’s climatic conditions, the air-conditioner is used during more than 90 per cent of the trips, whether short or long ones. At the very least, once every 60,000km or every four years, whichever comes first, the system should be serviced by a workshop specialising in auto air-conditioning.

During this service, the whole refrigerant network should be flushed fully and the existing refrigerant discarded completely. This would also remove any foreign particles that may have been deposited from deteriorating elements such as the internals of the receiver-dryer or expansion valve.

A proper job means replacing at least the receiver-dryer before recharging with fresh refrigerant.

The more frequent “service” to perform is the replacement of the air filter for the evaporator in the car. This filter inevitably picks up minute particles from the outside air. A choked air filter creates an increased resistance to the airflow past the evaporator and naturally reduces the overall efficiency. Generally, the air-con filter should be renewed at least every 25,000km.

Most drivers prefer to keep the Recirculate switch on all the time because it reduces the load on the compressor and cools the interior faster. Nonetheless, it is important to frequently allow fresh air to enter the cabin. If and when you do so and detect a faintly stale smell, it means the filter is overdue for replacement.