i have a Audi a6 c6 2004 2.0 TDI i have being putting antifreeze in. i think there might be a airlock i have done what i says on the manual

Open bleeder screw -arrow-.
– Fill up with coolant until it flows out at bleeder hole in coolant hose.
– Close bleeder screw.
– On vehicles with auxiliary heater, switch heater on (for about 30 seconds) and then off again.
– Tighten filler cap on expansion tank.
– Start engine.
– Set heater/air conditioner on both sides to “HI”.
– Run the engine for 3 minutes at 2000 rpm.
– Allow the engine to run at idling speed until the two large coolant hoses at main radiator become warm.
– Run the engine for 1 minute at 2000 rpm.
– Switch off ignition and allow engine to cool down
Check coolant level.
l The coolant level must be at the MAX marking when the engine is cold.
l The coolant level can be above the MAX marking when the engine is warm.

why i thing it has a airlock is because when it gets to the proper temperature and i put my heaters on the temperature goes down to half way between 50c and 90c is this normal please help. it dose not over heat and i get heat out of the heaters

 

Since you have heat, then the coolant completes its cycle through the whole system. Also, you don't overheat, which it means the fans are kicking in as they should.
It sounds more like you have a coolant temp sensor problem - the unit that sends the temp to the dashboard panel gauge.

 

i have never noticed the gauge going down before since i put the the antifreeze in

 

Try cracking open the bleeder screw again. It could be that you have a bubble but it will work its way up to the bleeder eventually.

 

You just said that:
...and you bled the system right, hence my supposition.
However, an air pocket may cause that temp fluctuation read as Bob already pointed out.

 

I'm not sure the system is the same as in my 04 3.0 but mine has another bleeder under the plastic cowl panel over the battery. On the heater hose to the driver side (USA) of the battery,you have to pull back a fabric sleeve and open a hose clip to pull the hose back on the pipe to expose an opening in the pipe, which is the bleeder. If yours has this bleeder, you may just need to burp it there.