Engine thermostat failure.
Hot water valve or hot water valve vacuum driver is faulty.
The inlet and outlet pipes of the heater are blocked or the heater core is blocked by dirt.
Temperature control damper or control cable is damaged.
The air conditioner blower is damaged or the blower control circuit is faulty.
Air conditioning distribution pipe is blocked or leaked.
There are many reasons why there is no warm air in automobile air conditioning. It is not recommended that the owner repair the car by himself, so as not to cause further damage to the car. Go to the local after-sales service as soon as possible to help the staff solve the problem as soon as possible.