Engine Coolant

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Engine coolant is the key element of the heating system. The normal engine operating coolant temperature is controlled by the thermostat. The thermostat also creates a restriction for the cooling system that promotes a positives 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 heat of the coolant flowing through the heater core is absorbed by the ambient air drawn through the HVAC module. Heated air is distributed to the passenger comfort. The amount of heat delivered to the passenger compartment is controlled by opening or closing the HVAC module temperature door. The coolant exits the heater core through the return heater hose and recirculated back through the engine cooling system.