Engine Coolant

WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

Engine coolant is the important element of the heating system. The thermostat controls the normal engine operating coolant temperature. The thermostat also creates a restriction for the cooling system that promotes a positive coolant flow and helps prevent cavitation.

Coolant enters the heater core through the inlet heater hose, in a pressurized state. The heater core is located inside the HVAC module. The ambient air drawn through the HVAC module absorbs the heat of the coolant flowing through the heater core. Heated air distribution to the passenger compartment, through the HVAC module maintains passenger comfort.

Opening or closing the HVAC module temperature door controls heat delivered to the passenger compartment. The coolant exits the heater core through the return heater hose and recirculates back through the engine cooling system.