Interior heater issue. cold air when fans at full speed

[Navisace]

hi
got a bit of a issue with the heating system. A3 2.0 tdi (150) 2013 44K
when the fan setting is at lowest speed warm to hot air comes into the cabin but as soon as the speed is anything over a 1/3 the air goes cool.

i had the timing belt and water pump changed in summer and did not realise this issue then so i cant say that it actually happened then. have changed the internal heater flap motor also the auxiliary water pump in engine bay.

scanned the car with vcds and all is showing ok so an a bit stumped now. cant find anything on the threads with this issue apart from the matrix being blocked but have had the the coolant changed last week but still issue.

any help would be much appreciated as it is getting chilly out there..

cheers in advance.

nav

 

[Navisace]

hi does anyone know where the Interior Heater Control Servo Motor Actuator is located please
i have searched and nothing on the net

 

[richinsoton]

it sounds like an airlock in the heater matrix to me & the cooling sytem needs rebleeding with the heater temp set to max heat to ensure fluid flow through the matrix.

 

[Navisace]

Thanks
I will get it bleed again this week although garage assure me they bleed it