my mk 2 renault clio is constantly overheating i have checked the thermostat thats fine, checked the radiator fan thats working when hotwired but not in engine. the radiator & hoses are all hot and the gauge is at the top but fan still not working.
so the radiator & hoses and thermostat all working but fan is not what can this be

PAUL FULTON, May 2010

Sounds like thermostatic switch in radiator not working. You can test it by checking circuit continuity when it gets hot. Remove it from the radiator, place it in a saucepan of water and heat it up. Use a multimeter or test-bulb to check that it makes a circuit (i.e. switches on) when it gets near boiling point. If it doesn't, then replace it with a new one. Use a new O ring gasket to avoid leaks.
See also:
http://www.renaultforums.co.uk/showthread.php?s=1b36217252f2f363be0271bacaa66e49&t=70909&page=2

ChicksFan, May 2010