Why does it smoke when the heater cab is opened after the small heater tank is repaired? I suspect the new small water tank is leaking. No smell of antifreeze!

I have encountered a similar situation before, and the air conditioner refrigerant leaked. The smoke is thin and a little choking. At first, I thought it was dust in the air duct, but it was not cured after treatment. If you can't repair it yourself, you must go to the repair shop to find the leak, stop the leak, and add refrigerant again after treatment. If everything else has been checked, there is no problem. This is probably it.