Cooling fan fault.

[Addison_80]

Looking for a little advice regarding the radiator cooling fans. What is the correct temperature for them to cut in? Mine are cutting in just above 90 mark. Problem is when the come on there is an obvious drain in power when the kick in (lights dim for a split second) and it sometimes sounds like there is a short circuit under the dash on the drivers side. I'm thinking sticky solenoid but was wondering if anyone else has had a similar issue?

[s2driveruk]

what model - 3B/ABY? I'd get this bottomed out asap as it can end up frying the harness and fuse plate (BTDT )

[Error404]

If its an ABY, the 3rd fan speed kicking certainly dips the revs at idle, it's a beast and draws a lot of current. The sounds under the dash could well just be the large relay that drives it. As David says though, check it out though as the fan draws a lot of current and a fire could easily happen if there is a major problem with it.
Not sure on the exact temperatures, i think the 2nd speed comes in at around 92 and the 3rd speed at about 100.

[S2central.net]

Buzzy noises under the dash will be for third (highest) speed fan operation - could be a sticky relay alright... I cannot remember the fan switch temps but think its well documented on S2central. Best way to test relays & wiring is to jumper the radiator switches with suitable connectors (these are low current switched on the relays).

Remember that the lowest speed (1) is for after-run (triggered by the thermo switch on the water rail) and only relevant when ignition is off
Speed 2 is when the first temp switch in the radiator is closed (hot water with ignition on)
Speed 3 is when the 2nd temp switch in the radiator is closed (very hot water with ignition on)

[s2driveruk]

Here you go, I knew it was here somewhere with some tests etc too:

http://www.s2forum.com/forum/showthread.php?t=1043&highlight=fan+testing

[Addison_80]

Cheers. Its an Aby yes. That linked post hits the nail on the head i think. Seems that its skipping the second stage fan and going straight to the panic mode fan stage. Will have to have a look today.

[Michael S2]

Is there any leaks from radiator or hoses?

I was struggling to keep temps down below 90 when stationary. A leaky return pipe hose shortly followed by a leaky radiator probably the result of a block somewhere seemed to be the cause. New hose and rad and fan now keeps temps below 90 at all times. Might be worth flushing and bleeding the system.