LUVTruck.com

OK, so I have gone through a good amount of the threads involving switching over my 79's Plastic fan to an Electric. Now I've never installed or wired an Electric fan before and was wondering, I've been hearing of some people preferring the ones placed in front of the Radiator but behind the grille or behind the radiator. I've also gathered I'd need to buy a Electric Fan Relay Kit with the Thermostat. Can someone school me on how the relay and thermostat works in conjunction w/ the electric fan and will I have to upgrade any of my electrical system to produce enough amps to run it ? My main goal is to give the stock 1.8 better cooling capabilities as it is both going to become my DD/Trail Rig.

I'm looking at this fan as Summit has both 10" & 12" Electric fans that are reversible and can be used as a pusher or puller.
http://www.summitracing.com/parts/SUM-G4902/

What type of Electric Fan Thermostat Kit w/ relay will work ?

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1979' LUV Mikado 4x4 1.8L 4spd, 3" Body Lift, 235/75/15s Scrambler wrapped around Centerlines, Pushbar w/ KC Lights, Bed Roll Bar, ect.

A "puller" fan behind the radiator is usually the best option, if it fits between the engine and radiator. The only time you should run a "pusher" is if there isn't enough clearance. With a thermostat and relay, your system should work like such: You have 2 seperate circuits. One should be a fused circuit (whatever rating your fan calls for) running to the "high current" terminals of your relay, then the fan, followed by ground. The other should be a fused circuit (5A or so) running to the thermostat, then the "low current" relay terminals, followed by ground.

The thermostatic switch closes when the probe reaches a certain temperature, which closes the relay terminals, in turn allowing the fan to run. When the temperature drops back down, the switch opens, opening the relay, which cuts off the fan.

The thermostat is there to keep you from having to constantly eyeball the temperature gauge while manually switching the fan on and off. If you want, you can wire an override switch in parallel with the thermostat in case of failure. A relay needs to be in this circuit because electric fans draw a lot of current, usually in excess of 20 amps. A lot of toggle switches can handle that kind of current, but you risk early failure, especially if you draw your current through the ignition switch. A thermostat will probably burn up in short order if it is wired in series with a fan.

As for your alternator, if you have a plastic 4-blade fan, then I'd bet you don't have A/C. If this is the case, you have a 35 amp alternator which probably won't last long with the extra load on it. The alternator for A/C-equipped trucks is rated at 50 amps and is a direct bolt-in replacement. I would use this alternator.

Finally, any thermostat/relay combination will work with any fan. Just make sure the thermostat switch is set to close at the temperature you want. My '76 shop manual shows the normal operating temperature to be 180 degrees F. Hope this helps!

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-Micah
05 GTO 6.0
85 Yamaha RZ350

This is a helpful discussion. An electric fan conversion is on my to-do list (although it hasn't yet reached the top of the list). I have a/c so of course it needs to run whenever the compressor runs. However, I'm trying to decide if I'll need a diode in the circuit to keep the thermoswitch from activating the a/c compressor.

I'm thinking about just adapting a fan and the wiring, relays, etc. from a VW or some other vehicle. I had a 1980 VW Rabbit that had all the necessary stuff to turn on the fan when the a/c compressor came on.

Jack

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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.com
IsuzuPup.com

Instead of using a diode, you could run a second relay in parallel with the thermoswitch, closed by the A/C compressor switch. That way, when the A/C compressor kicks on it effectively bypasses the thermoswitch. It's more work than simply using a diode, but it would get the job done and the compressor switch will be electrically isolated from the fan circuit.

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-Micah
05 GTO 6.0
85 Yamaha RZ350

I like that idea, thanks. Since there's already a relay that's closed by the A/C switch, I'll call the thermoswitch one the "second relay" (hopefully harvested from the same donor vehicle as the electric fan). It's easier to wrap my brain around it that way.

Jack

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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.com
IsuzuPup.com

The thermostatic control that I used in my setup has a separate wire (a green one I think), that connects to the AC clutch switch and turns on the fan when power is applied. I have it wired to a switch in the cab so that I can turn on the fan when I want to (no AC in my LUV)
Also, I used a pusher fan because there's a lot more room in front of the radiator than behind it. I removed the stock mechanical fan and I still havn't had problems.
A mechanical fan uses about 5 hp... and with only 80 in the first place, that makes a big difference.

All 4x4 trucks have a 50 amp alternator, so no worries there, but if you go from the 35 to the 50, wiring is gonna get smoked if you don't swap it out alongside the alternator.

I found all my stuff on feebay... I'm using an adjustable thermostatic fan control made by Derale. Never had any problems with it. You won't have to worry about diodes or multiple relays, and it's worth the time.

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1980 4X4 LUV daily driver, as stock as can be.

Just got back from local junk yard with an electric radiator fan relay and some of the wiring. Looked under the hood of my truck for a location to place the temperature sending unit/ switch for the fan relay. I don"t see an easy place to install one. I thought about tying in to the sensor for the temp light but the previous owner installed a temp gauge so the sensor registers a variable resistance now so that is out. Does anyone have any thoughts on this. My truck in an 82 diesel 4x4.

Thanks

Jer

I just replaced my water pump this past week after reading this topic.
How could it take 5 hp to turn that tiny little plastic fan?
Even if you get rid of the fan, you are still turning the water pump pulley.
I just can't see it. My comment is not meant to dis anyone, but I would think it must
be the guys who make the electric fans who are putting those numbers out there.
Or maybe the 5 hp comes from the number it takes to turn a fan on a big V8 or something.

I can not say it is exactly 5 hp saved but the drag on the engine doesn't come from turning the fan per say. The power is consumed when the fan creates high and low pressure areas that move the air and create resistance. Think of a paddle on a boat. Turn it narrowly through the water and there is little resistance. Pull it on the wide side and resistance grows. Electric fans are more energy efficient in that they are only used when absolutely necessary, high engine temp or a/c. They are not used when traveling down the road itself moves adequate air to keep the engine cool. Also remember engine driven fans are designed to keep the engine from overheating on a hot day at idle.

ok guys, i have a question for you.

from my reading, i have come to understand you need a few things for the install.

1.) An alternator to handle the amperage draw
2.) the fan itself
3.) perhaps an install kit


In regards to the alternator, i just installed a 50 amp alt from an AC equipped Luv. (brand new from O'reillys)
as far as the fan goes, i have my eye on one that hayden cooling makes. i think it's a 10 inch, but i may be mistaken. it does look, however, like it will indeed fit.

the real question is the wiring and install kit.
most controllers that we stock at work (O'reillys) use the push in probe that sits between your radiator fins.

Personally, i dont like the idea of having to rely on a contact probe. i was wondering if the temp gauge sensor/sending unit can be used to trigger the fan's operation?

besides that. does anyone have a basic schematic of how the wiring for the fan is supposed to be set up?

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To the Oquirr hills for awesome thrills! Go-go 4wd, Activate!

I highly recommend a SPAL fan. I installed a 16 inch puller low profile with the new fan gasket that allows it to be placed against the radiator, It is controlled with the PMW speed controller for quiet operation and a very long life. I will check this weekend and get all the part #s I used. It is very well made. The 16 in just does fit inside the tanks of the original radiator. The fan does an exceptional job of cooling my truck. The system is almost plug and play with waterproof connectors. Just like OEM. SPAL has been in business for a very long time and produces OEM and aftermarket fans. Check out their web site for a ton of info. www.spalusa.com

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1980 4X4 LUV

Here is a the site I bought mine from. Plus they have an enormous amount of info. www.a1electric.com

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1980 4X4 LUV