If your vehicle is showing heater takes a long time to get warm, here are the most likely causes and the parts you'll need to fix each one.
The thermostat regulates engine temperature by restricting coolant flow until the engine warms up. If it fails in the open position, coolant flows to the radiator constantly, preventing the engine and heater from reaching operating temperature quickly.
The heater relies on hot engine coolant flowing through the heater core. If the fluid level is low due to a leak or evaporation, hot coolant may not reach the heater core efficiently until the engine is fully hot.
If the cooling system wasn't properly bled after a recent coolant flush or water pump replacement, trapped air can block the flow of hot coolant to the heater core, causing delayed or intermittent heat.
Over time, neglected coolant can cause sediment and rust to build up inside the heater core. This restricts the flow of hot coolant, meaning it takes much longer for the cabin air to get warm.
The actuator controls the blend door that directs air over the heater core. If the motor is failing or the door is physically sticking, it will delay the transition from cold to warm air entering the cabin.
If a relay or temperature sensor fails, the radiator cooling fan might run constantly from the moment the car starts. This overcools the engine and significantly delays the warm-up process.