Air and Cabin Filters
For such a simple device there sure is alot riding on air filters. This item protects your vehicle from potentially harmful destructive components entering the engine airstream. Sand and other fine particles can wreak havoc on the longevity of your engine. Further a clogged/restrictive filter will effect power and mpg efficiency.
The air you breath is just as important as what the engine does. The cabin filter helps to mitigate harmful pollutants including pollen and dust from recirculating around the interior of your vehicle doing it's best to keep your family safe. Additionally the filter helps prolong the life of various havc components by protecting against case intrusion. A clogged or restrictive filter will cause your hvac to work harder to keep your interior cooler as you lower the temperature and increase the fan speed in turn causing the compressor to be engaged longer putting additional strain on your engine- decreasing in mpgs. Repeat replacement of relatively inexpensive part sure provides a nice safety net to you and your vehicles well-being.
If that sounds far fetched ask any fleet owner. AC use can decrease your gas mileage upping the cost of each trip, changing a dirty cabin filter increases ac system efficiency.
Are there reusable variants of filters?
Yes although an initial higher cost if your one who is considering hanging on to a vehicle replacing both the cabin and engine filters with reusable varients will save you money in the long run.
My defrost settings on my vehicle are not as efficent as they once were can a clogged hvac filter contribute to this?
Yes. A clogged filter would restrict air flow which would reduce air volume flowing across the evaporator the item that directs the dry warm air to the bottom of the windshield reducing efficiency.
I've heard others mention finding evidence of nesting on hvac filters is this true?
Absolutely in fact in occurs so frequently that I have lost count how many rodents I've encountered servicing such filters. Think of it another way the filter is the only stop between the rodent entering the blower motor compartment.
Graphic scare tactic ahead but absolutely true that has occurred multiple times
In the most neglected of cases I have encountered vehicles with infrequently serviced filters the rodent eventually chewed through the filter falling into the blower housing. Customers come by explaining of either a dead smell or a weird blower noise or inoperative blower. I encounter what looks like a rather large but not dense mouse pelt. Thinking that was odd I look up. The the centripetal forces of the blower drained the mouse of blood. Some customers want me to replace the blower some want me to replace the case. I can clean the case to the best of my accessibility but some passages are so small there is not a way to realistically clean them. Might be breathing mouse dander and it's other diseases it carried as a host body for awhile. In short check the filter frequently.
But why do they nest there?
The reasons are multiple 1. Easily accessible for the rodent's. 2. Infrequently disrupted by humans. 3. It is a relatively soft yet stable surface. 4. The temperature will be hot in winter and cold in summer. 5 depending on location the filter maybe near an evaporator- evaporators byproduct is moisture-moisture pools to water- aka they have a water source.