Same problem over here, but different cause and fix (Laguna 1).
The whole cicruit is under-dimensioned, so anywhere the cable/connection can burn out. This is not surprising as the heater draws a lot of current in particular when cold.
In my case the plug that connects to the fusebox was burned out. This is accessible by first losing 4 stone
, and diving on your back under the wheel near the pedals. The rear window heater is on the yellow connector, the thick white wire.
This is also where the relay is located if you were looking for it.
In order to fix it, one can replace the connectors on the fusebox and the wire. I did a quicker (and dirtier) repair:
- take out the responsible relay. Crack open its case carefully with some pliers.
- Solder a foot long wire on the relay that connects to pin 4. After making a hole for the wire in the relay case, put back the relay case back on with some tape or glue.
(decent thickness electric wire, there is a lot of current flowing here). Plug it back in its old position.
- Cut the heater cable from the yellow connector and attach it to the new cable coming from the relay.
Works fine, and saves a lot work.
I can put up pictures if needed.