I thought these were helpful, enjoy
BASIC AIR CONDITIONING PART 1
http://www.youtube.com/watch?v=2wZb6HgIDE0
BASIC AIR CONDITIONING PART 2
http://www.youtube.com/watch?v=j1nYipLAv0U
HVAC ESSENTIALS
http://www.youtube.com/watch?v=8EEl7hLBgGM
UNDERSTANDING HVAC
http://www.youtube.com/watch?v=R9rh5kCsEAk
REFRIGERATION CYCLE
http://www.youtube.com/watch?v=gSmaXrj6u9A
https://www.youtube.com/watch?v=mWVFXwhyn8g
https://www.youtube.com/watch?v=nOdUUFT9no4
HEAT PUMP
http://www.youtube.com/watch?v=NyNeh7wPQQk
http://www.youtube.com/watch?v=14MmsNPtn6U