From what I can see, the resistor pack is usually connected to the firewall, but I couldn't see one when I checked my own car. Google "mitsubishi resistor pack" to see what I mean and select "images". It can't be far away from the matrix. You could always call mitsi....or ask a garage to show you, if they think they will get a bit of work from it. Tell them you want to source the part and ask them them to show it to you.
EDIT:
Re: Removing/replacing the heater matrix
Unread postby bluemajor » Sun Feb 19, 2012 10:45 pm
under glove box small gold coloured squaremetal box held on with 1screw and fed by 2 wires
97 Manual GPX. Icecelle Blue.
Other Stuff: Induction kit. Front Strut. Apex Lowered. 17" Kahns. Quad exhaust. HID lights. Glow dials and rings/cups. Black leather seats. Window tints. Sunroof.