vfr800 cooling fan not coming on

84c is a VERY low temp to come on - my 6th gen its 106c Normal running temps are 78c (on the move) & anything up to 110c in really bad (Stationary) conditions...

 

I believe the coolant display is taken from the coolant temp sensor which may not be the same temperature at the fan switch, but would be closer if the entire system was evenly stabilized at that given moment.... The service manuals don't give a temperature....... however, the thermostat starts to open 80-84C and should be fully open at 95C.... perhaps 84C is a bit low, but maybe better tested a few times to confirm a better average?

 

@raYzerman , @Diving Pete I too was surprised it came on at 84c I was expecting mid 90's tbh. I think @raYzerman has a point, we are leaving on a long trip tomorrow. I will post a pic below. So we should get a good indication of the temp the fan comes on on average.

looks to be around 1300k's

 

Hello, first time caller here.

Did anyone ever get to the bottom of this? I have a 2006 with the same problem, no fan.

Fan comes on when the wire is grounded, just fitted a new genuine radiator switch and nothing. Switch should come on at 100c I left it ticking over up to 107 before I bottled it and switched off.

Coolant is to the top. Fuse is good. Fans work when manually over-ridden against the metal of the radiator. Temp comes down pretty quickly when I override the switch so I don't think I've got a blocked rad. When driving at normal speeds the temp sits at about 78c which is what I'd expect, espiecially at this time of year. I'm lost as to what to try next? Any ideas?

 

I think there's a chance I've got either a blocked left hand rad, or there's air trapped up in that corner next to the fan switch.

I'm going to try and flush the rad tomorrow, and then refill and burp the system on the side stand to try and remove any air. I can slacken off the switch a couple of turns too to try and release any air that might be trapped up there. Hopefully it'll help. I'll report back if it works!

 

The fan power is supplied live to the motor, with the connection to earth being through the switch and then the radiator body.

You have shown the fan to work when jumpered to a ground (the radiator) so there's no supply side issue. I think you're on the right track considering whether the switch is airlocked, but another possibility is the connection between the switch body and radiator, is there a chance it has some threadtape that is causing it to be insulated? A quick continuity check between the switch body and radiator would eliminate that one.