98 (C4) A6 avant 2.8 and after the overflow bottle cracked and I lost some coolant, temp of the heater went warm, no longer hot.
I replaced the overflow reservoir and had NTB flush and fill/bleed the system.
They are adamant that it is fully bled, but when i asked them about the bleed they said they do not use a vacuum.

So I still have no heat at idle and a little under load.

But, since the flush/fill/bleed, the temp gauge seems to get to the 1/3 block (where it always used to sit) while idling, but stays lower when under load.

They started feeding me some stuff about the thermostat being bad and the top hose temp being higher or lower (suggesting they were the wrong way round temp wise), but I can't see why the thermostat is duff.

Is this just air in the heater matrix thing?
Any pointers how to get that damn air out?

Thanks,
Alex JB

 

I would believe the thermostat is bad. I'm pretty sure that even idling you should get the temp gauge about half way. The thermostat is what allows the coolant to get hot, if it starts to die and just stays open all the time the fluid is always being cooled by the radiator and never gets hot.