- Upper heater hose: Connects to the water pump outlet on the front of the engine, and runs to the heater core inlet on the firewall.
- Lower heater hose: Connects to the heater core outlet on the firewall, and runs to the bottom of the engine block water pump to circulate coolant back into the engine block.
When reconnecting the heater hoses, ensure they are securely clamped to prevent leaks. Also, ensure your coolant mixture is appropriate for your climate to prevent freezing or overheating issues.