Just noticed the passenger side airflow from vent and dash are very low. Drivers side works fine so I think it may be a dislodged pipe? Is it easy to check the pipework behind the dash?

 

In a word, no.

And it gets worse the younger the car is.

You MIGHT see something if you remove the glove box, and then lie upside down on the passenger seat.

But: what might have dislodged it? Could it be blocked? Sucked in a wadge of leaves etc?

 

Hmm I'll take a look this evening and see if there's a way in! I've not had the car long so not aware of and blockages. I've got a feeling this will be a lengthy fix...

 

Remember it could be dislodged/blocked at either end.

 

Update: pipework seems fine where I could check in (inside car). Also blocked off the vents and played about with forcing the air to the dodgy vents which did increase the flow drastically.

Next thought is a blockage near the fan but have no idea where that's located?

 

Fan is on top of the heater matrix, I believe it's a dash out job?