Electric fan question

[Roger63]

So I have dual electric fans on the radiator. It's wired through a relay and it grounds through a thermo switch screwed into water pump housing. It keeps blowing the thermo switch about 2 days after installation. This is the 2nd one and I am running out of ideas.

 

[moparedtn]

Short in the wiring or one (both?) fans pulling too many amps? Fuse ought to catch it first...

 

[Roger63]

Short in the wiring or one (both?) fans pulling too many amps? Fuse ought to catch it first...

I don't believe anything is wrong with wiring. If I bypass the thermo switch and go directly to ground they will run all day.

 

[moparedtn]

I don't believe anything is wrong with wiring. If I bypass the thermo switch and go directly to ground they will run all day.

So your guess is you've run into a bad batch of switches by chance?
A meter solves this riddle pretty quickly perhaps...

 

[Roger63]

A meter would work fine but the switch remains open.

 

[derush]

So I have dual electric fans on the radiator. It's wired through a relay and it grounds through a thermo switch screwed into water pump housing. It keeps blowing the thermo switch about 2 days after installation. This is the 2nd one and I am running out of ideas.

did you wire it as per the instructions ? i think the thermo switch is supposed to be wired to trigger the relay which will power the fans , these fans draw way to much current and the thermo switch cant handle it , thus burning them up . check online for this wiring diagram if you dont have one . $.02

 

[Roger63]

did you wire it as per the instructions ? i think the thermo switch is supposed to be wired to trigger the relay which will power the fans , these fans draw way to much current and the thermo switch cant handle it , thus burning them up . check online for this wiring diagram if you dont have one . $.02

Well I think so, I wired it so the thermo switch is completing the ground.

 

[derush]

it should be completing the ground on the relay side

 

[derush]

it should be completing the ground on the relay side

and alot wire in a separate toggle switch with a wire to ground , so if the thermo switch fails to work they can over ride it with the toggle switch

 

[kiwigtx]

A simple diagram of how to wire the relay and switch below.

Sounds like you have full load current of the fan passing through the switch. If the switch was shorting, it wouldn't last the two days.....high current failure might take the time you are describing here.

or....

 

[Roger63]

and alot wire in a separate toggle switch with a wire to ground , so if the thermo switch fails to work they can over ride it with the toggle switch

Yeah I picked one up today.

 

[Roger63]

A simple diagram of how to wire the relay and switch below.

Sounds like you have full load current of the fan passing through the switch. If the switch was shorting, it wouldn't last the two days.....high current failure might take the time you are describing here.



View attachment 1286508

or....

View attachment 1286509

I will get a diagram tomorrow of how I have it wired, the only difference I see by your diagram is I have the 12v source for fans coming direct from battery. So I don't over load the relay.

 

[derush]

relays have different amp rates , make sure your relay can handle your load( both fans ) sometimes the load is so high (amps ) you need to run a maxi fuse to protect it

 

[Roger63]

relays have different amp rates , make sure your relay can handle your load( both fans ) sometimes the load is so high (amps ) you need to run a maxi fuse to protect it

That's why I wired the 12v supply to the fans directly to the battery, but thanks.

 

[Roger63]

Well I have to eat crow, went over to my neighbors to look at his system again to confirm what I was trying to do and we both wrote it down wrong.