Heater controls reversed?

Hello,

If this just happened suddenly, it could be due to a faulty blend door actuator.
The blend door actuator is what controls the hot to cold and cold to hot after the turn the knob. It is possible for the connectors to be shorted and getting reversed signal.

The blend door actuator is located on the HVAC box under the dash on the passenger side.

Here is a helpful article:

https://www.2carpros.com/articles/replace-blend-door-motor

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.