What size of fuse

[grannyknot]

Electronic Fan Controller 70 Amp

This is the electric fan controller I just picked up, it has a 70amp relay and they are recommending a 70amp fuse for the main power wire, now from what I understand the 70 amp relay is to handle the momentary power surge it take to get the fan going and up to speed but a 70amp fuse doesn't sound like it is going to protect much. Aren't wires going to melt before a 70amp fuse blows?

Thanks,

Chris

[SteveJ]

Well, if it's 4 AWG or larger it won't.

This is where it is important to know the fuse curve. Instead of trying to explain it imperfectly, I'll post this link: http://www.cooperindustries.com/content/dam/public/bussmann/Electrical/Resources/solution-center/technical_library/BUS_Ele_Tech_Lib_Time_Current_Curves_How_to_Read.pdf

Basically, you might need 70A for inrush, but that is only for a short duration. I think a 20A fuse would work, but you would need 12AWG or larger wire for the circuit.

[EuroDat]

Hi Chris,

The controller in your link has a built in 70Amp relay, but that doesnt mean your fan will pull that much. RelaYs have an over capacity to help prevent the contacts burning.

You need a fuse to suit the fan your using. Do you have and specs for the fan your planning to use?

Chas

[grannyknot]

Steve, I plan on using 12ga wire.

Chas

More Information for DORMAN 620105

It's a 13.5" A/C fan, don't know the cfm but it is quite powerful.

[grannyknot]

Oh, and it's from a 1996 Ford Taurus.