Mk1 fabia vrs heater smell

Wouldnt let me post in the mk1 forum for some reason.

I’ve had a burning coolant smell coming through the cabin fans for a while now and can’t seem to find the problem. I’ve changed the heater matrix along with the pipes as that was leaking on the inside of the cab when I first got the car. Now that’s sorted when the fans are on hot it’s still got a bad smell, I’ve also noticed there’s dried coolant in the heater channels which go to the rear footwells under the front seats. Is it possible coolant is in these heater channels and won’t go away until they’re removed and cleaned? Would it mean taking all the dash out to clean behind the vents properly? Only way to get rid of the smell it to set the fans to cold and shut then fins