Hi Manuru, I suppose that in this model does not carry cold boot cable, so look at the 50A fuse first. lest there be some short circuit in heating wiring, then check the temperature probe and measures resistance between poles 1 and 3 must give 20º about 980 to 1180 ohms, if it is outside these values, it may not be signal to act for the heating module, (if the probe is fine, also check that it reaches current to this module)
* If you want more information, I recommend you download the manual Ibiza-Cordoba/97 "In the Manual Section (there comes your engine) Greetings !!