HVAC
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    car
    truck
    rv

    Why Is There No Heat From My Vents?

    Typical repair cost: $30–$1,500

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    Common Symptoms

    Cold or lukewarm air
    Heat only at highway speed
    Defroster will not clear windshield
    Sweet smell
    Foggy windows

    Most Likely Causes

    1

    Low coolant

    Heater core needs coolant flow; low system means no heat.

    2

    Stuck-open thermostat

    Engine never warms up; gauge reads low.

    3

    Clogged heater core

    Restricted flow blocks heat exchange; sometimes back-flushable.

    4

    Failed blend door actuator

    Clicking under dash, vents stay on cold side.

    5

    Water pump failure

    No circulation = no heat anywhere.

    How a Shop Diagnoses It

    1. 1.Confirm coolant is full and engine reaches operating temp.
    2. 2.IR-thermometer both heater hoses — both should be hot.
    3. 3.Listen for blend-door clicks at the dash.

    When to see a professional

    Sweet smell + foggy windows = leaking heater core. Park it; coolant fumes are toxic.

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