I have a ford fiesta 1.25 lx 1997 and the heater will only function on full (knob on 4).On the same day the rear window heater stopped working. Are these connected (loose connections)?
sounds like a resistor, try under the glove box in passenger footwell, adj centre console. remove a small black screw and you'll see a large resistor with a 4 wire plug connection. check the state of the connection, its prob melted so you'd need to replace it, a scrapyard will sell you a resistor for around 15-20 quid.
ryan mac
January 2009
The heater fan will be the resistor pack burnt out! it's behind the sidetrim in the passenger footwell, £20 from ebay, as to the Heated rear window, Fuse, Relay, switch, contacts on the bootlid, or the tags on the windscreen fallen off (my mk4 had the tag on the earth side of the heater come away )
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Try fixfault.com to fix cars.