Diamond

First I changed my charcoal microfilters today after a couple years probably and the heat and a/c come out wayyy hotter and colder-world of difference. Mine were filthy.

One thing I was wondering for the heater-does it heat up most quickly with recirc on or off?

Dandle

The car will heat up quicker with recirc on as it will be pulling the air from the cabin which is warmer and putting it though the heater. Don't keep it on all the time though as you will end up with the a/c system smelling because of no fresh air through the system.