When the airconditioner is turned on in the front cold air comes out of the
front vent and hot air out of the rear vents.
What is the problem?

 

Hello and welcome to the forum! It's either the blower motor is faulty or the heater control valve is stuck. I would start with those two in troubleshooting. Please let us know if you have any other questions or if we can assist with any part needs in the future.