Cabin Heater Problems

[Lg32]

Hi,

I have a 2013 a3 2.0tdi crbc engine code. Recently had aftermarket cambelt and water pump (gates) job and since then is only blowing out cold air. Engine runs up to temp fine no overheating and didn’t overheat before the job but heaters were okay. I can’t see the silca bag in the expansion tank so I hope it’s been removed before my ownership. I’ve tried heaters on full when running car up to temp no cap on tank to try and work airlocks out with no joy. I’m guessing my next step would be a back flush on the heater core, does anyone have any ideas what may be causing this 

Thanks,

Lee

Edited April 3, 2022 by Lg32

[Steve Q]

Definitely worth getting a flush. Could be a thermostat issue. 

[Lg32]

1 hour ago, Steve Q said:

Definitely worth getting a flush. Could be a thermostat issue. 

Hi Steve, thanks for the reply.

By a flush do you mean back flush the heater core or just flush the cooling system as a standard flush has already been done with the cambelt and water pump job. If it was the thermostat at fault, am I right in believing

Thermostat stuck open : I start the car after sitting overnight and the coolant temp rises as it should (maybe slightly quicker than other cars I’ve had) and maintains 90 on the readout then I should get some heat once the engine is warmed and I ask for it from the heating controls. 
 If it was stuck shut wouldn’t I get some heat as it warms and the coolant /engine would overheat? 

Apologies in advance if my understanding of this system is basic.

thanks, Lee 

Edited April 4, 2022 by Lg32