Flushing out Heater Core/Radiator to fix heating issue??

[RumpleForeskin]

I have had an issue with little to no heat and a malfunctioning temp gauge. I replaced my CTS the other day and that helped the gauge to at least reach the middle sometimes. Still fluctuates though, and no heat. I am going to try and flush the heater core tonight. Is it the 2 metal lines by the battery going towards the dash? What is the easiest way to do this? Also, will i be able to run on straight water until i get the VW dealer tomorrow for g12?
Thanks!
01 Audi A4 Quattro 1.8t 5spd

[zrowcool]

no those 2 lines are for the a/c. best way is to flush the entire system with the engine running so that it will all be cleaned. make sure to have the heater on on high. if its not too cold then it fine so leave the water in for a day. if it is cold there then i would just wait

[geeky]

I just did this today. My temp gauge would be erratic moving around from the second tick mark above C to halfway and would randomly move around depending on speed etc.

I followed the DIY from audidiy and continually flushed out the system using water for a good 10-15 mins then refilled it with G12 (50/50 with water) The temp gauge now is CONSTANT at 2/3 tick marks above C. That still seems wrong to me, so going to replace the CTS tomorrow.