Thank you for your answer to Mike's post (thank you Mike). For my case, it looks like that the problem is with overheating protection. And since:
1. max airflow is really huge, and climma in aft works even with medium flow
2. I see 220v on electrical heating element constantly
3. On the other hand I can't hear any relay clicking, at the moment when heating is gone
4. Current in the heating circuit is dropped from 5a to 0, at that moment
I think that the root cause is inside the heater itself, i.e. it could be one of those two things on the picture (since they are sitting in series with the heating element and basically can break the circuit), the below one looks like thermistor, and the one above:
Is this the klixon thermostat marked on the picture?
How did you clean it, if it is the thing?
Aleksei @ Aletes SM2K#240