I am new here. I need help. I can't locate the air filter for my Carrier 58STA. I looked at the owner's manual and it shows that there should be an air filter compartment adjacent the unit. I have attached two pictures. Since I didn't see an adjacent compartment, I thought that may be the air filter would be behind the door in the first picture. As you can see in the second picture, I didn't see any access to an air filter after removing the door. Any ideas or suggestions? Thanks.