New Fan Wiring

[Joel]

Just installed a spangly new SPAL fan, which draws just under 18amps. All the wiring seems up to the job, with the possible exception that I have a Revotec thermostat thing in the top rad hose, which came with it's own mini-loom and relay. The wiring on that seems unusually thin compared to the wiring on the new fan, and I can't find anywhere in the fitting instructions any reference to what kind of power it can handle

 

I've run the fan continuously for 20 minutes or so, and the suspect wiring didn't seem to get overly hot or anything, but just to put my mind at rest - do you think it's ok?

 

Also, one strange thing I've noticed - the fan was a straight swap and didn't involve any new wiring, but now for some reason the engine continues to run for 5-10 seconds after the ignition is turned off. It never did that before! Nothing else has changed. Any ideas?

 

Cheers, Joel.

[Guest turbo]

when it runs on is it only when the fan is spinning if so i have heard this before something to do with feedback and the fan motor acting like an alternator or something

[Guest salty_monk]

Mine used to do that sometimes when the fan was spinning!

 

18 amps is a hell of a lot for a fan. My CBS one used to draw 5 amps at start & settle down to two or three. Ford one I had only used to draw 12 at startup I think.

 

If you've run it for 20 minutes & it didn't get hot it should be ok. It draws most current on startup.

 

Dan

[Longboarder]

The sensor/switch is only using small currents to activate the relay. The wires to relay terminal 30, 87 to fan and fan to earth should be hefty.

I think Jamie is right about the fan motor turning its momentum back into electric if it is spinning when ignition is switched off. This would backfeed the ignition for seconds if it is connected to an ignition live. Try connecting it to a constant live feed or better still use the circuit Jim gives on the NW Hoodies site.

 

Nigel

[Guest salty_monk]

Mine was wired the NW way... Still showed those symptons tho doc...

 

[RedTrev]

Hi,

When an electric motor is switched off transient voltages can be seen, sometimes in the order of +/- 250v. These transients can do damage to electronic equipment such as Engine Control Modules or other ECU's unless they are fitted with front end supression. Some SPAL fans have transient spike suppression built into them and others don't. They are quite popular for heater units (we use them here at my place of work - LTI vehicles -we make the black cab you get into on a Friday and Saturday night!) I suggest you add a suppression device to your fan to "iron" out these spikes before you start to see things fail. Try a V22ZA1 which is a varistor available from RS or somewhere similar. (RS part number 649-122 ... they cost pennies)

This may not stop overrun but it'll protect your electronic bits if any fitted! Fit it in parallel across the fan.

 

Trev

 

V22ZA1