Understanding how your car AC system works

Thursday February 6 2020

If you notice that your AC does not reach those

If you notice that your AC does not reach those refreshingly cool temperatures, have it inspected. Photo by Alex Esagala  

By Roland D. Nasasira

The car air conditioner (AC) system only runs when you turn on the AC button or knob, which in turn, also switches on the air conditioner pump. For the AC pump to go on, it has to have AC gas filled to full capacity. This gas cannot be measured with your physical hands but rather a machine at a gas station.
Different cars, for instance John Kateeba’s Toyota Nadia can take AC gas of up to 800 grammes.
Other cars have different AC gas capacities written on different car parts such as the bonnet. The capacities range from 550 to 1,100 grammes.

Last month, which was characterised by hot temperatures, Kateeba could not imagine driving his Toyota Nadia without a functional AC. When the weather became hotter, he drove to a fuel station to have his AC gas filled and the entire system serviced.

Thamson Kawongolo, an AC technician at Nissan Motorcare on Jinja Road, says the AC system in your car is made up of hot and cold air. However, the functionality of the cold air that most motorists use is affected by different factors such as the clogging of the carbine or pollen filters.

These are manufactured inside the dashboard and you cannot be easily accessed unless by a technician.

The carbine or pollen or AC filter are all parts that mean the same thing and play a role of filtering the air you breathe in when all the car windows are raised up. These parts also protect the evaporator from being clogged with external dirt. The evaporator is a radiator-like part that produces cold air that is supplied to the car interior through vents.

“If your technician checks the carbine filter and it is not clogged with dirt, they have to check whether the low pressure pipe is cold enough by opening the car bonnet. The coldness that you or your technician feels from the low pressure pipe means that the coldness inside the evaporator is enough,” Kawongolo explains.


Causes of carbine filter clogging
When you look at the switch of the car AC system on your dashboard, there is a visible arrow that curves inside a car icon.

This, according to Kawongolo illustrates that air circulation takes place within the car from the blower to the car occupants and back to the blower. This mode of usage, he advises, is the recommended position for motorists who do not drive with lowered car windows.

When you also take a closer look at the same AC switch button or on its sides, there is another car icon with an external arrow, as if emerging from the car boot, entering the car. When you turn your AC knob to this arrow, it means that external air enters the car when you turn on the AC.

It means the air being supplied to the car occupants, with all nature of dirt, is from outside the car, but not the air that circulates within the car.

Proper use
“This explains why you turn on your AC and you inhale or see dust circulating in the car through the AC vents. It means you have opened the flaps that prevent dust from entering the car. This affects the performance of the evaporator and lifespan of the AC. In a short time, the carbine filter and the evaporator will be clogged with the external dirt entering the car and you will be exposed to flu or other AC dirt illnesses,” Kawongolo adds.

When the carbine filter is clogged, it also affects the performance of the evaporator. In the end, it also affects the AC cooling system.

When driving in urban areas, Robert Kakumba, an AC technician in Kisaasi advises that you use external air for a short while but that when you change to murrum roads that have dust, stick to the internal air circulation knob that guarantees a much longer AC lifespan. This means you would be preventing external dust or dirt from finding its way into the AC system.

Much as there may be no driving habits that damage the car AC system, Kakumba agrees with Kawongolo, reasoning that the main risk is selecting the AC knob for internal circulation to the arrow or knob that allows external dirty air to enter the car, thus clogging the evaporator.

This explains why you will likely develop AC flu illnesses or sneeze and you conclude that your AC produces dust yet you do not service or replace the carbine filter on time.