Hot air blowing only from passenger vent issue

[2007GTI]

Old Heater Matrix was removed, it was full of sand and gunk, similar to that video posted above.

Only issue now is, there is a slight drip, as the old O rings are knackered and the new matrix didnt come with new seals and clamps. They are fortune OEM, and odd size, will seek out some tomorrow, so far found these on ebay:

https://www.ebay.co.uk/itm/136625413835?

LLL says the above part no has been super succeeded by this, but mine look nothing like this:

https://www.ebay.co.uk/itm/136298974330?

[Rudedog]

Very odd isn't it with the sand like gunk - if it's casting sand then surely that would potentially affect 10's of thousands of VW vehicles - something doesn't add up to me.

[2007GTI]

To be honest i haven’t seen it in person yet, will do when i pick the car up, but it sounds the same. The coolant looked normal in the bottle!
My mechanic said he talked a lot of VW folk and they said they do a lot of heater matrix, and from what I’ve found online I believe them.