Hello pavlo,
Sorry for my late response.
About the seq number if I turn on the AC with seq 12345 I can’t turn it off with the same seq number.
Another test I did is, if I turn on AC with seq 12345 I can rise the temperature using the same seq but if I want to lower the temperature I need to change the seq, otherwise nothing happens.
If you can do some more tests as I say.
I’m not a professional developer but I think I can help you in some tasks, talk to me in PM 
Thanks mate.