On a scenic you can only access it by removing the top dash board cover, which is not that hard to do! Remove both the speaker grills, they just clip on. Once they are removed you can then see the two 20 torx screws that hold the cover on. Remove both screws, then put the steering wheel down to its lowest position. Push up on the front edge of the dashboard to unclip it. Once the front edge is unclipped, lift the front edge upwards and then pull the dash top towards you. The heater resistor is on the passenger side, but it is obscured by one of the large plastic heater pipes. Simply disconnect the pipe to access the resistor pack. there are two connectors going to the pack, squeeze the tabs and pull to disconnect them, unscrew the resistor pack and replace it.
BOB, May 2010
