Where would I go to learn about my HVAC system and mechanical material?

I m filling out a form that requires current gpa and the grade program I use doesn t show gpa so I calculated my gpa by adding all my grades together and dividing by the # of class...

So my average for each class so far is an A+, but in one quarter I got a B. Does gpa count specific grades, or just an overall average for each grade?...