Obstructed Coolant Flow

Possible locations or causes of obstructed coolant flow are as follows:

• Low coolant level
• Inoperative water pump
• Inoperative thermostat
• Pinched or kinked heater hoses
• Improper heater hose routing
• Plugged heater hoses or supply and return ports at the cooling system connections
• Plugged heater core

If proper coolant flow through the cooling system is verified, and heater outlet air temperature is low, a mechanical problem may exist.