You say your linkage is working well and the ratio is reasonable (a real short arm on the door might make for twitchy response).
Then what you're seeing is probably just what you'd expect. A big blast of hot air due to all the super-heated metal in the system dumping all that heat at once.
Does the temp settle down after it runs for a few minutes? Mine (-7) drops significantly in cold weather after 60 seconds.
Bill (Wild) VA-165 '90-'93
First Flight 7/17/2021!! 200 hours 6/22
- Been there, Donated 2022