(2) Thermostat, because the thermostat was removed or not installed during the previous maintenance, or it was damaged in the normally open position, so that the engine water circulation was always in a big cycle, the external temperature was low, the heat dissipation was good, and the engine water temperature was difficult to increase, so the warm air was not hot. Solution-Add or replace a new thermostat.
(3) Warm air water tank and heat exchanger. Reason-(a) Although the vehicle coolant is antifreeze now, it is not absolute to say that it is rust removal and corrosion protection. After a long time, impurities will still be produced. Usually, when we are maintaining the engine, red glue or other impurities will enter the waterway. (b) Some automatic transmission models are equipped with a heat exchanger on the gearbox, and the engine coolant enters the warm air water tank through the heat exchanger. If the heat exchanger is blocked, the warm air will not be hot. (c) Some models have exhaust ports near the heater water tank, and incomplete exhaust will also lead to the heater not being hot. Solution-If there is an exhaust port, exhaust the air first. If you can't touch the two heating pipes by hand and the temperature difference is great, use a water gun or air gun to directly connect the heating tank or heat exchanger.
(4) The heater control mechanism, the reason is that the heater can't be used normally due to the damage of air conditioning panel, cold and hot servo motor, heater water valve and other parts or the circuit failure of the heater system.