Sunday 11 March 2012
Replaced Your Car's Cabin Air Filter Lately?
Many vehicles made after 1990 have a cabin air filter in the AC/heater (HVAC) system. Have you ever wondered why? It’s not just to clean the incoming air as the name suggests.
A couple of things happened to vehicles in those years that made cabin filters a great feature. First cars got smaller and evaporators – the unit that cools the air – got smaller. Second, the industry refrigerant changed from R-12 or Freon to R-134a because of ozone depleting substance regulations.
Older, large evaporators had lots of space around the tubes and fins for moisture from the air to run through without freezing. Dust, pollen, bacteria that came into the car through the fresh air intake was washed out quickly by the freely running water. The smaller, more compact evaporators were redesigned to increase efficiency but they had little space for water flow. They also ran a bit warmer which didn’t pull as much moisture out of the air as before.
Since the muck didn’t wash off it sat on the evaporator and, when warmed up, smelled like a combination of rotten gym socks and a bad chicken sandwich. Customers complained and it was quite a procedure to clean the mess off and reduce the smell.
Along comes the cabin air filter which filters the dust and pollen before the air gets to the evaporator. Problem solved.
But, now, without periodic filter service, air flow is restricted resulting in poor AC performance in the summer and poor heater in the winter.
They aren’t cheap, but they really work. Manufacturers specify replacement intervals which are the minimum. In dusty, warm, dry climates more frequent replacement is required. Don’t try washing them. They’ll disintegrate and become useless. Many service counters have a clean vs. dirty cabin air filter display. Trust them. They are real.
Bottom line: replace the cabin air filter before AC season starts in earnest. It’s good for business and good for customer satisfaction when the HVAC works as it should.