The principle of air conditioning warm air is different from that of air conditioning refrigeration. Warm air is completed by the heat of engine coolant, that is, the coolant circulated by the engine enters the small water tank in the evaporation box of air conditioner through the pipeline, flow valve and circulation valve. After the blower rotates, the air flows to the small water tank, and the air becomes hot due to heating, which can be blown out through the air outlet of the air conditioner.
In this process, there will be many electronic and mechanical components such as air outlet sensor, evaporation box temperature sensor, flow valve, circulation valve, water temperature sensor, control unit and so on.
If there is no warm air in the car, let's first determine whether the following air conditioning outlets are out of the air and cool. If there is no wind, it may be that the blower is damaged, or the air conditioning filter element is dirty and blocked, or the damper motor is damaged or the flap is stuck, or there is wind at the air outlet, but it is not hot air.
If the warm air is not hot, it is not complicated to judge:
First check whether the engine water temperature is normal. If it has been in a low temperature state and does not reach the working temperature, the warm air will definitely not be hot. At this time, we can focus on whether the thermostat has been in a large cycle state or whether the signal of the water temperature sensor is true, and repair or replace the faulty factory.
Second, we should focus on whether there is a large temperature difference between the inlet and outlet pipes in front of the warm air box. If this happens, the heater box must be blocked and needs to be disassembled, cleaned or replaced.
Thirdly, it depends on whether the flow rate and temperature of coolant entering the heater tank meet the requirements. The temperature can be measured by infrared thermometer, and the flow can be judged comprehensively through the diagnostic data and fault storage of the detector. Common are pump loss and damage, warm air flow valve and coolant circulation valve.
Fourth, it depends on whether there is air resistance in the coolant system, which is usually not exhausted after replacing the coolant. The special cylinder gasket is damaged. Standard coolant discharge methods can be used for further confirmation.