2007 Heater Problems, controls or matrix?

[paddy1001]

Hi All,

Been lurking here a while now and only recently came back into vw ownership again. I bought a 2007 2.0tdi 140bhp passat about 3 months ago and have noticed recently that the heater is very very poor on it.
The car reaches working temperature quickly enough but the air inside the car only goes lukewarm at best even after a 50 mile run.
I have the controls with 3 knobs for adusting heat, fan speed and direction.

My question is what is likely to be the culprit with this? A blocked radiator core? The heater controls on the dash? or is there an electronic valve to turn the water flow to the heater matrix on and off?

I was doing a bit of looking under the dash at the past weekend and I found the flap that controls the air flow to the heater matrix is being powered open and closed as it should when you turn the temperature up but I was wondering if this should be proportional to the heat required as mine is either fully closed ( heat turned to 18) or fully open (heat turned to anything above 18)?

Is there a valve in the cooling system for shutting the water to the heater core? The pipes going into it at the bulkhead do not seem to be anywhere near as warm as the rest of the coolant pipes?

Thanks in anticipation

Paddy

[niall campbell]

there should be a thermostat from engine which opens to allow hot water to come in, check it ; if fitted !! follow the pipes back from bulkhead

[paddy1001]

Well just to update I found the problem today! But not fixed yet.
The coolant is turning into a jelly like substance which is blocking the heater matrix. I flushed the mattrix twice and it worked for about ten miles then blocked again.
Why on earth is this happening and how do i stop it?

[Alan G H]

It sounds as if you will need to flush the complete cooling system (probably several times) and put new coolant in. Be careful not to leave plain water in while the weather is freezing.

[RichardSEL]

Well just to update I found the problem today! But not fixed yet.
The coolant is turning into a jelly like substance which is blocking the heater matrix. I flushed the mattrix twice and it worked for about ten miles then blocked again.
Why on earth is this happening and how do i stop it?

What colour is this "jelly-like substance"?

[niall campbell]

sounds like lack of anti freeze at some point rusting things. Maybe heater matrix chocked up or radiator core ?? I would also consider changing expansion cap to get pressure in the coolant system to increase water circulation. Expansion cap and taking your radiator to a radiator specialist to check flow is your cheapest options first !!

[martin1810]

ANTIFREEZE - PASSAT

This might help explain your situation.

[Alan G H]

Martin, This was the first time I have visited your site, but it definitely won't be the last. Lots of very useful information, thanks.

[paddy1001]

What colour is this "jelly-like substance"?

Hi,
The jelly substance is green in colour, same as the coolant. I bought the car about 3 months ago and one of the first things I did was a new timing belt, water pump and coolant because the stuff in the engine was a dirty brown colour.
The week after this one of the coolant hoses bust and I lost a bit of coolant, replaced this and topped the coolant up again.
In the last few weeks the heating inside got steadily worse till no heat at all.
I flushed the heater matrix twice yesterday and it was noticebly better both times but quickly went back to no heat at all.
I agree that I have no option now but to flush the entire system a number of times then refill with coolant but am wary about it doing the same again.

Thanks for the help and suggestions all, keep them coming!

Paddy

[RichardSEL]

Hi,
The jelly substance is green in colour, same as the coolant. I bought the car about 3 months ago and one of the first things I did was a new timing belt, water pump and coolant because the stuff in the engine was a dirty brown colour.
The week after this one of the coolant hoses bust and I lost a bit of coolant, replaced this and topped the coolant up again.
In the last few weeks the heating inside got steadily worse till no heat at all.
I flushed the heater matrix twice yesterday and it was noticebly better both times but quickly went back to no heat at all.
I agree that I have no option now but to flush the entire system a number of times then refill with coolant but am wary about it doing the same again. Thanks for the help and suggestions all, keep them coming! Paddy

This from Martin's excellent site: "The high levels of Silicates in older G11 antifreezes can react with the inhibiters in G12 type antifreezes to produce a yellow/green sludge. So it makes sense to avoid putting G12 type antifreeze in a G11 filled car. "

Mine's now a red colour after being changed and flushed. Was a low yellow colour (supposedly topped up at main dealer at their last service) The indy that changed the timing belt and water pump used G12+ spec. If you stick with a 50/50 mix of that then you should be alright. Hope it gets sorted... Let us know how you get on?