Hot Rod Forum banner
1 - 20 of 20 Posts

·
64Joker
Joined
·
324 Posts
Discussion Starter · #1 · (Edited)
I'm converting over from a mechanical fan to an electric SPAL fan and will
be installing a simple "on/off" switch.
There are only 2 wires involved (red/hot and blk/ground) and the on-off switch.
If I run the hot wire back to the fuse box at the "ignition" connector, will I need to install a fuse between the on/off switch and the fuse box? Or will the ignition connection provide the required protection?

Can I ground anywhere, or should I ground at the on-off switch?

Make: Chevrolet
Model: Impala
System: 12V
Engine: 327 cui
Year: 64
 

·
Registered
Joined
·
3,111 Posts
If I were you I'd install a relay...... Connect a 10 gauge wire to the starter lug or the battery (good strong 12v source) into a fuse (same amperage as the fan motor) into one side of the relay, other side of the relay to the pos side of the fan motor lead..... you can attach the gorund side of the motor to any good ground...... then use your on off switch to control the relay coil. I'd also advise you use a temp controller to automaticlly control the fans etc.....

I attached a simple dia.... it only one fans but two could be attached easily.... if you put in the temp controller it would be where the switched 12v line is etc....
 

Attachments

·
Dennis W. Parks
Joined
·
56 Posts
I agree with EOD Guy in that you need a relay. If you don't install a relay, you will be replacing on/off switches on a pretty regular basis. A relay is probably less than five bucks at the local auto parts store, so it is not like they are expensive.

A temperature sensor is a great idea as well, as that will allow you to forget about the fan and let the temperature of the engine control the operation of the fan as required. With or without a relay, if you simply use an on/off switch, you will need to remember to turn the fan on to prevent a hot engine, and then remember to turn it off to avoid a dead battery.

Dennis W. Parks
Author of automotive how-to books
 

·
Registered
Joined
·
3,111 Posts
As to your original questions.....

"If I run the hot wire back to the fuse box at the "ignition" connector, will I need to install a fuse between the on/off switch and the fuse box?"

That would depend on if the "Ing" connector you are tapping into is protected by a fuse and which side of the connector you tap into. If you tap into the always hot side of the connector then yes you should put in a fuse and it should be at the same rating as the max amp draw of your fan....... If you tap into the fused side of the connector then .... no you don't need a fuse, be warned, if your Ing connector fuse is smaller than the max draw of your fan .... you will be replacing some fuses and I would not recommend you put in a larger fuse to compensate because then you byspass the lower amp protection to the original circuit it was protecting etc....

"Or will the ignition connection provide the required protection?"

See above

"Can I ground anywhere, or should I ground at the on-off switch?"

There are two ways to do this..... ground one side of the fan and run a pwr wire back to the Ing connector, as you mentioned above..... or Run the pwr wire from the Ing connector, as you mentioned above, to one side of the fan..... making the fan Hot at all times then running the other leg from the fan back to one side of your switch and the other side of the switch to ground.

You have to make up your mind how you want to wire it...... both ways will work....... But I still recommend you use a 3 dollar relay and wire as explained in my eariler post.
 

·
64Joker
Joined
·
324 Posts
Discussion Starter · #6 ·
EOD Guy Follow-up...

As to your original questions.....
You have to make up your mind how you want to wire it...... both ways will work....... But I still recommend you use a 3 dollar relay and wire as explained in my eariler post.
Well stated/explained, I will get that 3 dollar relay! Your follow-up is greatly appreciated...
 

·
Registered
Joined
·
179 Posts
I also am wiring up an adjustable electric fan with a relay. I opted to run the lead to one of the "always hot" open fuses in my fuse panel. My thought is that when I park the truck after driving, the electric fan will be able to run until the engine reaches the adjustable fan's "turn off" temperature. I have had cars in the past that were wired like this from the factory and it seemed to make sense doing it that way. Any drawbacks to this other than the battery may have a little extra draw on it until the fan kicks off?
 

·
Registered
Joined
·
3,111 Posts
No, that's the way I have mine wired....... Mine has a "car off" delay feature. That is it runs for 1 min after I turn off the ing, the run time is adjustable up to 10 min.....
 

·
64Joker
Joined
·
324 Posts
Discussion Starter · #11 · (Edited)

·
Registered
Joined
·
3,111 Posts
The fan controller I used is from Dakota Digital.....they are proud of it tho" lol..... it was super easy to hook up, came with the temp sending unit, and all the wires/equip to connect it up, it has a fully adjustable temp on, temp off, one or two fans, adjustable cont to run after the key is turned off and most important, IMO, a test mode that allows you to test the on/off temps at any time...... it is a "fan always hot" and the module connects to ground, I like that because if the thing fries all I have to do is disconnect the relay wires from the module and connect them to a ground and my fans are running etc...... just a little insurance. I am very sat with it

That looks like a pretty neat relay/fuse combo, you can get away with a 30 amp bosch type relay, or a 40 amp...... you want the heavy duty contacts that the higher amp relays offer...... now you will protect the circuit with a 25 - 30 amp fuse......
 

·
the 'Duracell Project'
Joined
·
2,703 Posts
thanks for the info eod,
dakota has always been proud of their stuff
probably a couple of bleed off capacitors that keep the relay energized
a dimes worth of parts and $100 worth of dakota
i'll stick with my plain jane relay set up it :D
 

·
Registered
Joined
·
3,111 Posts
Yep..... If you already have a system, prob not worth the cost....... I started with zero and was going to have to purchase parts and pieces, temp controller, relays, wire, temp probe, bushing etc..... in the long run the DD was a little more but well worth it IMO
 

·
Get in, sit down, hang on
Joined
·
2,785 Posts
Hmmm ... reading this with interest, and always appreciate EOD Guys product knowlege and opinions. :thumbup:

I searched our NAPA catalog for "delay" (with the intent of finding a "headlights off" delay relay.)
I didn't find that, exactly, but this relay came up with various usage. (i.e. "A/C Comp Time Delay Relay", "A/C & Heater Delay Relay", and more specifically ... "A/C Condenser Fan Motor Relay "


NAPA Echlin #AR-143
NAPA SRP ~= $20.00 CDN

I'm thinking this might be worth a call to the tech line to see if there is an integral timer built in???

Thoughts?
Opinions?
 

·
Registered
Joined
·
3,111 Posts
If you guys are looking to add a delay timer to a relay...... check into a delay timer module for a house alarm system...... most work on 12v and if you use it to control the coil on your fan realy it might just work...... I've never used it for this type app..... but I have used them to control some devices I use in teaching.
 

·
Registered
Joined
·
3,111 Posts
As far as your dia..... it will work as long as you provide a ground to the coil side of the relay. The 30 amp fuse before your on/off switch is a bit of over kill and your relay coil will burn up long before that 30 amp blows
 
1 - 20 of 20 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top