smokeing 306

my mum has a 1998 1.4 306 with air con and all the toys.she rang me to pick
her up because smoke was pouring out from under the dash on the passanger
side.i have had a good look and it had blowed 5 fuse's.i have also checked
the wire's and there are two plugs by the heater motor,one is white one is
grey.i have found that the grey wire that goes into the white connecter
has all melted,does any body no what this wire is for because the manuel
does not say thanks

have you tryed by passing it and dos the fan work still?