HVAC unit or commonly idiom AC is most advanced and needy electro-mechanical device in our home. Without this device we can’t relax in the heat waves as environmental pollution has already been jumped over its limit. AC is acronym for Air conditioning and we mainly fall over its cooling side when summer knocks us badly. As other major appliances it also meets with some common accidents which may put us in trouble to look for AC doctor. But with few precautions we can avoid such headaches easily.