Heater 1.2 2007 9n

[Andrew S]

Hi All

I have no heater. Have removed both hoses going to the bulkhead and out the garden hose on full just in either port and water is not going through, no flow at all.
Immediately presumed blocked matrix but now wondering how the heater works as in where is the control valve.
I replaced the heater vent flap motor to the left of the glovebox (6Q2907511A), does this only control the vents or does it control the heat?
If not, then where do I go from here and presume the heater control knob either has a wire or cable running to the valve. Cant see any images in Google as yet
Any help appreciated

[littlepolo]

I think the heater core is straight through with constant engine coolant flow and hot air is a result of the flap valve directing incoming cold air over it. Are you sure there are no airlocks in the system? You could check the in/out ports of the heater core with an IR thermometer if you can get access. Also check ODB for any codes relating to the heater flap motor.

[Andrew S]

Thanks for your help

I have taken the pipes off the heater core from the engine bulkhead side and used garden hose in either outlet or outlet and there is no flow at all. One pipe from the thermostat piping is hot, the outlet cold. Presume the therefore the core must be blocked if there isn't a control valve attached to it?

Not sure if I could could use a descaler to try and unblock it?

Thanks again for your help
Andrew

[littlepolo]

Was the garden hose run both ways and under pressure?

Is there any flow at all? Is there any warm air at all at any time when driving?

I've heard of the silica bag in some coolant header tanks bursting and then blocking cores. Not sure if that is applicable in this case but unless it's solidified a reverse power flush might release it. However, you need to be very careful with use of tap water and cleaning the system properly after (suggest you check on the correct procedure - which you will need to use anyway since you have introduced tap water via the garden hose?). I think the correct procedure requires compressed air blown through the system after.

Not sure about use of a descaler (thought I'd be cautious with introducing any chemical agents into the system) though it might be worth looking into it. The risk is it loosens debris from the heater core that circulates to block the radiator cores.

One more thing, do you have a service history indicating that the correct spec coolant was used?

[Andrew S]

Thanks, yes heard of the silica bag issue. I understand the risk of using chemicals in the system but do have a compressor so could force out anything. Might do that first just in case chemicals attach the solder joints in the matrix.
Absolutely nothing comes out of the matrix either way it’s flushed with hose so has to be blocked.
Jobs for warmer weather I feel or more time. I need to remove the bulkhead pipes and instead add two long lengths of tubing and force air down or chemicals to soak then flush out.
All good gun

[littlepolo]

Various VAG forums do mention a blocked heater core as being quite common, though no clear cause is given. I suppose a degraded/incorrect coolant could start some kind of reaction and then fur up the heater core.

I would not rule out that a foreign body/part could be the cause of the block. I can't think of anything in particular that might be the cause but I have seen bits of hose and gasket on other vehicles. If anything strange was going on with the coolant it's usually obvious to see.

[Andrew S]

Thanks
Yes, will have a go with an airline first and then chemical’s but with tubing on both core ports only so nothing can get into the system
Cheers
Andrew