punto heater blowing fumes into car

[xrxr]

have a Fiat Punto 1.2 which has recently started to blow fumes out of the heater. Not sure if the fumes are from the exhaust but they are strong. This only happens when the heater is on the hot possition, when switched to cold its fine, but it happens whether the air is set to circulate or fresh.
I have been advised that it may be a leaky heater matrix on another forum, looking up pages on that subject seem to indicate that its a bit of a pain to sort out. Anybody else had to resolve this in the past?

 

[punto chris]

i could be wrong here, but i thought if the heater matrix was leaking then the water would be leaking on the floor therefore you would get wet patches on the floor?

someone plz verify this.

 

[arc]

check the crank-case/oil breather isnt leaking

 

[xrxr]

If the leaks are small then I might not yet be at the stage where I get the wet patches, but I do get the misted windows and am now convinced that the fumes are from the coolant so maybe not an immediate health risk but bad enough. I have read that this may be possible to fix with RADWELD or similar, has anybody had any luck trying this?

 

[arc]

radweld will just delay the invetible, it'll plug it - but one day it will go in a bigger way.

What do the fumes smell like, is it a sweet antifreeze smell - or more noxious? If it doesnt smell like antifreeze then its not your heater matrix

 

[Liam]

If its not the matrix then in some cases I've heard Radweld can actually block a heater Matrix so best only used as a get me home fix before getting the problem fixed.

Liam