This presentation provides visual aid to support basic principles related to heat transfer in buildings.
These lecture notes describe how insulation works.
This image shows the major components of an HVAC system. The outdoor compressor is purple, the return ducts are blue, the supply ducts are red, and the the thermostat is orange.
This presentation provides some helpful images related to (mostly poor quality) installation.
Source: Building Media, Inc. - published March 30, 2017
This video describes basic information about HVAC systems including types of systems, proper installation tips and potential design pitfalls.