1, probably because the heating pipe is blocked. In this case, it is necessary to clean the water tank with detergent to decompose the scale into powder, so that the water pipe will not be blocked.
It may be that the blower is out of order. The blower can suck cold air into the heat exchanger to absorb heat, and then blow hot air into the car. If the blower fails, it needs to be replaced with a new one.
3. The coolant circulation valve and flow valve may be damaged. At this time, the normal temperature and flow rate of coolant cannot be maintained, and there is no warm air in the air conditioner. Need to go to 4S shop to check the cause of failure, repair or replace.