What should I do when the swift warm air is hot and cold?

There is something wrong with the temperature-controlled damper, usually the program crashes or the damper drive motor/module fails.

First, set the air conditioner to "automatic" and try to adjust the required temperature. If not, please disconnect the negative battery for 3-5 minutes, and then try again.

Check whether the heating water tank is partially blocked or whether the air duct leaks. It is estimated that the possibility of air duct is small, because the temperature is the same in summer, and the biggest possibility is that the heating water tank is partially blocked.