WHY DOES THE FAN START WHEN IGNITION IS ON

[Jonny Tunnel]

Not sure whats up, but Bongo fan goes on when i put ignition on, without even starting the engine. Engine is cold, hasnt been used today.
Its a mystery ready to be solved..
cheers Jonny

[Driver+Passengers]

Not sure whats up, but Bongo fan goes on when i put ignition on, without even starting the engine. Engine is cold, hasnt been used today.
Its a mystery ready to be solved..
cheers Jonny

Which fan?

Radiator fan(s) or the scavenger fan just in front of the engine?

The sensor connections to check, respectively, are:

- temperature sensor low down towards the rear of the engine block on the driver's side
- sensor just behind the handbrake, poking down into the engine bay

Both sensors feed the ECU, which controls the fans.

[Jonny Tunnel]

Ok thanks, what should i be checking for?

[Driver+Passengers]

First off, which fan... then first checks are free - are the connectors attached, corroded? Otherwise, checking the wires, testing the sensors themselves...?

[Simon Jones]

Rad fans will also come on when A/C is engaged.

[Driver+Passengers]

I removed "are the blowers on" from my original post thinking myself rude, but if A/C was also on...

[Simon Jones]

In theory, A/C compressor will only engage when engine running, so it ought not to be that. My guess would be the engine bay sensor is open circuit resulting in the scavenger being on, but its not clear from the OP which fan is being referred to.

[Jonny Tunnel]

Im sorry i dont know what the scavenger fan is.
A/C is defo off

[Simon Jones]

Big one in front of the engine (roughly where the gear lever is). Then there are two more traditional fans behind the radiator.

[Jonny Tunnel]

i can hear it quite clearly so im guessing its the scavenger fan

[Driver+Passengers]

If you lift up the driver or passenger's seat - you can see the scavenger fan, just in front of the engine - angled slightly up the way. The radiator fans are bolted onto the back of the radiator, and harder to see (though you can feel the air with the seats up).

[Jonny Tunnel]

Nice one D&P, ta