Q7 2012 AUDI Q7 3.0 TDI I HAVE COMPLETLY LOST THE HEATING

[shan2022]

HI all, i have a 2012 3.0 tdi Q7, i was having issue of getting my car heated up after very long time sometime upto 30 mins, spoke to a mechanic he said start by changing your thermostat, which i did, since changing the thermostat i have completely lost the heating, he has made me change water pump and also radiator. but the car is still same, coolant remains cold even after running for hours, but when i drive it starts overheating. (it doesn't overheat on IDLE). radiator pipes also remain cold
CAN ANY BODY PLEASE HELP ME I DONT KNOW WHERE TO GO FROM HERE. I WILL HIGHLY APPRECIATE ANY HELP I CAN GET HERE.

 

[NHN]

Sounds like a blockage, circulation issue, is water coming back into the reservoir, could be matrix blockage.

 

[shan2022]

Sounds like a blockage, circulation issue, is water coming back into the reservoir, could be matrix blockage.

hi, water is NOT coming back into reservoir.
what do you suggest? what are your thoughts about air lock ? as it wasn't like that before i changed the thermostat.

 

[NHN]

Then use a vacuum unit to clear any possible air locks.

If no return coolant, not many things can cause that, so check them all.