This has a happened a couple of times now, always when moving at slow speeds. This is due to reduced air flow. temp shoots right up over 100c, I've always stopped and got cold water in the system.

The fan is not coming on at 95c like it would noramlly do, I've a Secs unit and reading the coolent temp on this. Some times the fan will come on other times it won't.

When driving on the motorway the other night I was getting cold air through the vents when the heater was on and then this would come through hot again.

I've taken it to a garage and they have said it could be the thermastat or a blockage in the rad, I'm thinking it might be a faulty fan.

Anyone had anything simalar in order to shed light on the matter.

It's booked it in monday for a new thermastat. if that doesn't work I'll try a new fan, failing that i'll replace the rad.

 

Wire the fan to run all the time m8, and see what you get?
If it fixes it, then replace the sensor.

dipster

 

Does the fan run when you put voltage direct to it? if not the fan is dead, unlikely though.