Ongoing Cabin Heat Issues Matrix

[Compo1]

Eh up

Thought id start a fresh thread as im a little bit miffed with cabin heat problems.

A couple of weeks back i switched out my heater matrix as i had no hot air, matrix was blocked when i tested after removal.

Flushed the system with DI water till it ran clear fitted a new Nissense matrix and replaced di water with g12 evo bleeding the system with VCDS.

Great heat until Thursday last week when vents got cold when blower was on full and heat set to HI.

Re bleed system with VCDS and there was no improvement, so yesterday i removed the new matrix and water flows freely through it, not blocked. Calibrated air direction flaps. I get hot air on a low blower settings, so for me the matrix just is not getting enough flow to keep the air moved on the max blower setting hot. Its not blowing water out of the header tank when it regens at this point.

So anyone know what the problem may be ?

I know there is an electric pump on the circuit, i thinks its the one near the oil filter TDI184. Is that right ? How to test this anyone know ? And there appears to be a heater control valve N82 in the circuit somewhere. Anyone know where that is located ?

 

[SuperV8]

i believe the electric pump (on the micro circuit) is only used on cold starts (when your main pump is shrouded) and when you shut your engine off - to keep circulating the coolant though the micro circuit (EGR) when hot.

When the engine is upto temp - it's your main coolant pump doing the pumping.

Are you sure your engine is getting upto temp? What are your oil temps?
Check your flow and return pipes to your matrix (you can feel them under the dash) the flow should be hot, and the return should be cooler as the heat has been removed by the matrix.

If your matrix is not blocked and you can hear your micro pump working when performing a system bleed - then I would say either your EGR could be blocked (reducing mirco circuit flow) or your engine coolant temp could be limited maybe by a stuck open thermostat?

 

[Compo1]

With the weather as it is water temp is at 90c with in car instrument panel in around 5-6 miles

Oil temp starts to approach 90c and above around 8 miles in to a b road journey mainly 40mph. Even with the oil temps of 90c and above vents got cold when blower was on full and heat set to HI.

It is baffling me im sure the motor flaps are working as they should well reasonably convinced i may have to revisit that. So that left the heater support pump but now its doubtful that is the issue as you say this is not active when car is up to temp which make total sense.

So this leaves a heater control valve N82 restricting flow to the matrix and im not sure it even has one . The hot water flow is not enough to keep the air moved on the max blower setting hot.

I wonder what N489 valve role is ?

So your point on the EGR been blocked how do a prove that either way ? Disconnect the water pipes and check the flow ? I can see that been fun

Thanks for your suggestions mate

 

[SuperV8]

With the weather as it is water temp is at 90c with in car instrument panel in around 5-6 miles

Oil temp starts to approach 90c and above around 8 miles in to a b road journey mainly 40mph. Even with the oil temps of 90c and above vents got cold when blower was on full and heat set to HI.

It is baffling me im sure the motor flaps are working as they should well reasonably convinced i may have to revisit that. So that left the heater support pump but now its doubtful that is the issue as you say this is not active when car is up to temp which make total sense.

So this leaves a heater control valve N82 restricting flow to the matrix and im not sure it even has one . The hot water flow is not enough to keep the air moved on the max blower setting hot.

I wonder what N489 valve role is ?

So your point on the EGR been blocked how do a prove that either way ? Disconnect the water pipes and check the flow ? I can see that been fun

Thanks for your suggestions mate

The N82 valve - is the shroud on the electro mechanical main coolant pump. Which should move in or out depending on cold start, these can get stuck but I would expect if it was stuck closed so there was no flow from the main pump then you would also have an over heating engine! so I would presume as you aren't over heating - and you get upto temp speedily like my car this pump/valve is working fine.

This leaves the EGR cooler on that micro circuit! They also have flow and return connections so you could check the flow through the cooler - but the trouble is getting to it! down the back of the engine

I would just triple check the flaps are working before tackling the EGR cooler.

 

[Compo1]

This leaves the EGR cooler on that micro circuit! They also have flow and return connections so you could check the flow through the cooler - but the trouble is getting to it! down the back of the engine

I would just triple check the flaps are working before tackling the EGR cooler.

Yeah seen the location its a scary place that

As the egr cooler is on the same low temp circuit as the Matrix would i not get away with checking the flow through the egr cooler by disconnecting the bulk head matrix pipes and sending water through those obviously not in the matrix direction but towards the block. ?

 

[SuperV8]

That might work - though only one of the matrix pipes goes to the egr cooler - the other egr cooler pipe goes to the head.