A D2 HVAC Heating challenge

[Nognar]

Evening All,

Over the years I always seem to have problems with heating, my D3 had a blocked Matrix and the D2 S8 works perfectly but is always hot out the left vent.

Anyway.

My 2003 2.8 QS D2 has little or no heating.

Not the end of the world I thought, some basics should be covered and I can get it working again.

Though I have to admit this one has currently stumped me.

Hence I thought I would ask the wisdom of the collective.

So to cover the basics for what I have done already:

1) No fault codes on VAGCOM

2) I have run through the basic settings 08 HVAC and all flaps seems to move/ work as expected

3) I have flushed the cooling system, put on a new expansion tank and topped up with pink to the correct level

4) Car drives as it should, does not lose coolant and keeps at 90c as expected

5) I have flushed the heater matrixes and while they were dirty they have been flushed clean with no blockages

6) Using a laser thermometer the pipes into both and out of both matrixes get to 40 to 50c so seem to be getting coolant/ heat as expected

7) There are no air locks or leaks and I have bled everything

8) If I have the fans on low there is a little heat can be felt on the middle and rear vents

9) If I turn everything up to high and the volume of air coming through seems to drown out any heat that is in the system

10) The HVAC works for cold no problems and I can move the air around the cabin as expected with the controls

So this one has been a bit of a challenge and I have spent a few weekends looking into this one to try and resolve it as winter is here.

I purchased 4D0959617A Water Pump valves as whilst they seemed to work I was going to replace it to make 100% sure. Though interestingly the car is fitted with something different, not sure if someone has been there before on trying to fix this,

I have some Water Pump Valves in there, but the ones fitted to the car do not have round motor part on the back with the Denso sticker. Most odd, so not sure if this is a genuine part they fitted for that year or someone has bolted something else in there to try and fix it.




So it may or may not be at fault but I have the wrong part anyway.

The only other strange item of note is on 08 HVAC measuring block 14 the LF Vent Temp G150 is always really high (30c to 40c) compared to the RF Vent Temp G151 which is about 10c.

I looked at the S8 blocks and both vent Temps were about 10c so I am not sure if this is a faulty temperature sensor that's causing the HVAC not to blow any heat?

So we have a strange one here, any thoughts would be appreciated.