Heating problems.

So few days ago I was successful to obtain a nice looking fabia 1.4 2001 hatch. Car overall is mechanically in good condition and drives well, but I'm right now breaking my head around heating system. I have no hot air and I can't change air direction. It's blowing cold air on passengers side no matter what I do. Heating box don't have flap motors (except the one next to fan motor, and its working) it's all manual with gears, levers mechanicly connected to heat knob and direction knob. As far as I could see all works fine - gears turning and on inside somethings moving. I removed one of the side vents and checked inside flaps are moving and it increases air movement a bit but still bout 95℅ goes to passengers foot. Could it be something broken inside box itself and not letting air out? Could thermostat be causing no hot coolant going to radiator (pipes to small radiator feel considerably colder than the rest of cooling system)? Before asking I browsed around quite a lot, but found forums only linked to faulty flap motors.

BTW.

I bought that car from a mechanic, so I assume that if it was a easy fix he would fix it b4 selling car.