A heater hose is a flexible rubber tube that transports coolant to or from the heater core in your vehicle. Heater hoses are important parts of both the heating and air conditioning (HVAC) and the engine cooling systems.
To keep your engine cool, engine coolant (also known as “antifreeze”) is circulated through the engine block where it picks up heat caused by combustion. The coolant is pumped out of the engine to the radiator. There, the heat dissipates into the atmosphere before the coolant returns to the engine to pick up more heat.
Some of that warm coolant is diverted from the engine to the heater core (similar to a radiator) located beneath the dashboard inside the passenger compartment. When the heat function is selected on the climate control center, the vent fan blows air through the heater core, and warm air enters the cabin. One heater hose carries the coolant from the engine to the heater core; another carries coolant back to the engine.
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