- Follow the heater hoses from the water pump to the heater core.
- The upper hose should connect to the top of the heater core, and the lower hose should connect to the bottom of the heater core.
Method 2: Check the Thermostat Housing Temperature
- Start the engine and let it run until it reaches operating temperature.
- Feel the thermostat housing. If the upper thermostat housing is much hotter than the lower housing, the hoses may be reversed.
- This method is not always reliable, as there may be other factors affecting the temperature of the thermostat housing.
