What are the reasons for a car's air conditioning not producing warm air?

[CourtneyDella]

The reasons for a car's air conditioning not producing warm air are: 1. The engine has just started, and the coolant temperature is still relatively low, so turning on the heater will not blow warm air; 2. The heater valve and heater core have malfunctioned, which can also prevent the car's air conditioning from producing heat. The car's air conditioning system generates heat by utilizing the engine's heat. The heating principle of a car's air conditioning is quite simple: during heating, the high-temperature coolant from the engine flows through the heater core, and the air blown by the blower also passes through the heater core, allowing the air conditioning vents to blow warm air. The heater core is a heat exchanger and is a critical component for the car's air conditioning to produce heat.