It's too bad no one was able to answer this question. I have about the same problem. I am mostly annoyed that the air from the HVAC system is either very cold or very hot. I can't find a middle ground between hot and cold. It can be very unfortunate at times. I have to turn on the heating at regular intervals on cold days to avoid getting fried inside the cabin. I've asked a lot of car enthusiasts I know. None of them could help me. My last hope is a car mechanic friend who took a special HVAC course at https://www.hvacschools411.com/by-state/. I tried many options, even replaced the AC amplifier, which was quite expensive.
Anyway, you asked about it in 2019. Were you able to solve the problem?
