Are the washable filters better than the disposable type?
Sometimes they are, but usually only slightly. They should be thought of as more convenient so you don't have to have a spare filter on hand.
Why should I pay for maintenance on my heating and cooling system? It seems to be working fine.
When a professional heating and cooling maintenance is performed, we look for things that can make the system use more energy than it needs to and for things that may cause a future breakdown.
Should I cover my A/C unit in the winter?
Only if small leaves or debris will fall on it and pile up badly or fall down into it and plug it up, otherwise it is not necessary. If you do cover it, it is recommended to remove the electrical disconnect to avoid accidentally turning on the A/C and causing damage.
How often should I change or wash my filters?
That depends on the size of the filter(s), the size of the heating and air system, and the type of filter used. The typical one inch disposable filter should usually be replaced every 1-3 months of use. Thin washable types are also 1-3 months in between washings. The more expensive pleated filters like the 3M Filtrete type will need to be replaced more often than lesser quality filters because they catch more dirt. They also restrict the airflow which can actually increase the system operating costs. We have large professionally installed box filters which are replaced usually 1-2 years and do a far superior job of removing dirt and dust without restricting the systems airflow.