2017 Prius 2 Blows Hot Air Driver Side Only No Cold Air

My prius suddenly started blowing very hot air driver side only and when AC and fan off but air outside to inside option is on hot air comes in and vents are very hot. If i keep circulate air inside and AC off Fan off everything is off. When I start my car cold in cold weather for few minutes cold air comes and then hot air starts coming driver side only. My neighbor who is a mechanic for school district buses says there is no leak in ac system after testing and it may be heater air door actuator. What do you guys think? Toyota dealership here wants $199 for just a diagnostic. Any easy way to find AC diagnostic codes for my 2017 Prius 2? Any help very much appreciated.