Hi, would anyone know anything about Heater problem pretty please ?

[Robaudi8d4]

Hi
Ive got an A8 d4 3.0 tdi 2011 ,

The heating is playing up, its hot to start with till it gets to temperature then it just goes really cold...ive found when i put my foot down hard , hot air comes out the vents for a moment

Ive changed the aux coolant pump under the wipers but no change at all.

Ive tried to bleed it at the bleed screw under wipers too....it came out alot then started to bubble then got to a dribble when it the engine got hot

when idling the pipes off the rad dont seem to get warm , i did it for 20 mins and it reached about 50 degrees without revving , then 10 mins of revving 60 degrees , i know it takes a lot to heat these engines up
but it seems a bit cold..i am getting heat really well for 10 mins though until it gets to temp so im a bit confused.

Any Ideas would be appreciated ?
Cheers
Rob

[Robaudi8d4]

just forgot to say there is no separate aux heater on my car

[Scott K]

You need to get a scan for fault codes. Find someone near you with VCDS. Might be a temp sensor gone.

[Robaudi8d4]

Cheers Scott , the only fault codes i have are these from carista ..would vcds show more error codes ?

Heater & air conditioning:
00130 - Lighting for door interior grasp back-right (L134)
00311 - Tire filler connector

Driver's door:
00920 - Heated Outside Mirror (Z4/Z5)

Infotainment system:
03276 - Testing Management Software version
03175 - Invalid Dataset
03623


Obtained with Carista 3.9.7 for Android

[A8Cruiser]

Te engine temp sensor (one of them anyway) is quite easy to change a shame it sits near the front in the V. (I think?)
Do it when the engine is cold though. Just a circlip, and socket.

Hope it is not your thermostat...

[Robaudi8d4]

Cheers ,ill try the temp sensor if its an easy fix first ... if it was the thermostat it wouldnt get hot at the start would it ?

[Robaudi8d4]

ive just pulled the bonnet and the engine is cold from overnight.. the fans seem to come on on the radiator within minutes and the engine is still cold ?

[Robaudi8d4]

mm seems like the fans come on when the air con /heating is on even when the temp is set to hi .. both hoses are cold on rad...

[Robaudi8d4]

just been out trying to burp it and when its to 80 degrees , the heat is set to hi not on auto ..the blowers blow out really cold air like its out the conditioner..
also when its to temp the bleed screw under the plenum is open and no fluid comes out...when its cold it floods out..

[A8Cruiser]

And this is with your climate set on Econ?

What happens if you set the middle vent to 'warmer' as IIRC, the middle vents on the D4 can be set to warmer or cooler air, like on the D3.