Hi All, Looking for some advice if possible - I have had a trawl through old posts but couldn't spot anything to answer this question directly .......  I whipped the heater of my 4 out of the car this afternoon because the matrix had been weeping so needs to be renewed - pipework plumbed back together to keep the car mobile. Without going down the Clayton route (pockets insufficiently deep)  is there a swap of fan (impeller or motor or both) that can be added to the existing heater box