I'm replacing my air filter on 2010 impala which made me think about HVAC filter. Difficulty? Different types? Do they make charcoal? Best type for allergies.

Your cabin filter is changed by taking off the vent covers located outside on passenger side under the windshield and wiper arm. You do not have to remove the wiper arm to get this cover off. And the cover goes 1/2 way across the bottom of windshield. Once you have access, the filter is easy to see and replace. As far as filters go, ask them at the parts store about different types of filters. As far as your gas pedal, have some one look at it to see if anything can be done.