Or allergies, for that matter.
I know that most people out there are probably like us who only gets their air conditioning units cleaned when it's already making weird noises or breaking down. But we have also learned that it's actually more trouble to wait because the performance of the appliance gets compromised when it's dirty. Plus, our health suffers too.
So, include the maintenance check up and cleaning in your household budget and yearly calendar, lest you end up suffering from a lot of allergic rhinitis episodes (that require medication!) and require a performance air filter just to get a good night's sleep. If you compute the cost, it will actually come out cheaper in the long run. Plus, a clean aircon unit also emits cooler air too.