GM Genuine Parts HVAC Heater Pipes are designed, engineered, and tested to rigorous standards, and are backed by General Motors. These heater pipes typically connect to your vehicle's heater hoses and aid in the overall circulation of coolant within your vehicle's HVAC system. GM Genuine Parts are the true OE parts installed during the production of or validated by General Motors for GM vehicles. Some GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment (OE).