I just bought an a3 1.6 tdi sport 2010 in November yes not the greatest decision I’ve made but hey here goes….Coolant level good, good flow, been flushed and pipes flushed. According to mechanic temp of blowers gets hotter when revs are high? Car not over heating so water pump is good! Matrix? Core? Thermostat ? Just don’t wanna throw loadsa money at it, any help is much appreciated 🤞🏻

If the cooling system has been opened or drained there is a good chance you have an air lock preventing flow through the heater matrix. An internet search will show a few methods to shift the airlock, but I have not faced the problem myself so I can not say which ones work.

On 11/29/2022 at 11:39 AM, cliffcoggin said:

If the cooling system has been opened or drained there is a good chance you have an air lock preventing flow through the heater matrix. An internet search will show a few methods to shift the airlock, but I have not faced the problem myself so I can not say which ones work.

Ok thanks cliff, mechanic doesn’t seem to think it’s a airlock even he is baffled 😕 

Thanks Stephen,

OK, if it’s not overheating during normal use, then why suspect the thermostat - unless it’s not getting up normal operating temperature with about 4 to 5 miles? 
Kind regards,

Gareth. 

4 minutes ago, Magnet said:

Thanks Stephen,

OK, if it’s not overheating during normal use, then why suspect the thermostat - unless it’s not getting up normal operating temperature with about 4 to 5 miles? 
Kind regards,

Gareth. 
 

your right Gareth but is it possible it can still effect the cabin heating and not effect the engine over heating ? Or should I just cross the thermostat fix off and have a new matrix fitted ? 

Thanks Stephen,

The coolant that passes through the heater matrix is the same coolant that passes through the engine cooling system, so if it’s getting up to temperature, then replacing the thermostat isn’t going to alter anything - unless as I question, and you haven’t answered - does it get up to operating temperature within  a maximum of 4 to 5 miles and stay at its ‘normal’ point?

At this stage, it would be an assumption that the heater matrix is at fault. 
You state in your reply to Cliff that your mechanic ‘doesn’t seem to think it’s an airlock’. Again, that appears to me to be an assumption, unless he has proved that by rebleeding the system! 
Heater control issue perhaps? 
Kind regards,

Gareth. 
 

Stephen, you have not answered Gareth's question about how soon the engine gets to normal temperature, to which I will add two of my own. Does the engine overheat, and has the cooling system been opened or drained?

22 minutes ago, cliffcoggin said:

Stephen, you have not answered Gareth's question about how soon the engine gets to normal temperature, to which I will add two of my own. Does the engine overheat, and has the cooling system been opened or drained?

No engine does not over heat, Engine gets to normal temperature as it should, cooling system has not been drained 

I am puzzled how the cooling system can have been flushed as you claimed earlier without opening it.

Be that as it may, your other information confirms that the cooling system, including the thermostat and pump, is functioning as it should. Your heater problem then can only be either a physical blockage such as a kinked hose, a closed valve, a piece of debris, a clogged matrix; or an airlock.