One side blowing cold air

[SlavC]

Hi I have problem with heating in my Audi c7 2.0Tdi Passenger side blow hot but driver side blow cold 

Heter matrix replaced and coolant and thermostat 

still the same cold please help  maybe recommend garage in Cardiff Wales

[Sid2020]

Sounds like a motorized flap may be jammed/broke on the heater box. When you say the matrix was changed I presume just the radiator not the complete heater box 

[mike71]

Could it be that the cooling system needs bleeding?