Outer Limits 4x4 Board

Hey Guys can someone help me with either of the attached diagrams I want wire my thermo fan so I can switch it off when going thru bog holes etc... but also want to be able to have it run normally switched by water temp. I also want an overide switch so I can turn it on constantly when she's workin' hard if some one can help me by modifying one of these diagrams for me to do the above and post it back up here that would be greatly appreciated NOTE: I don't have Aircon! Thanks in advance! Robb (BOGFROG).

Just replace the A/C clutch coil with an on/off switch. It'll act as an override as it acts as the parallel circuit. Those relays are standard ones, like you use for your driving lights. It's the same principle - you have high beam activated or thru a switch in the cab.

One thought though, you may want protection (blocking) diodes after the Thermo Switch and Control Relay as I'm not 100% sure if they like the reverse voltage going thru them when activated by it's oppossing switch. I think the relay may be OK but not sure about the Thermo Switch.

I think he is talking about controlling a temp sensitive thermo without an air con at all.

Does the thermoswitch earth onto the block when the fan is active?

If it does then the sensor should be on the otherside of hte relay (ie between terminal 85 and the ground).

What you want then is a single pole double throw center off switch. that works like this.



you would put the switch between the sensor and the #85 on relay with COM connected to the relay. and then L2 would go to the sensor while L1 would be earthed.

That way with the switch in the off position you would have no fan at all, when running to L1 you would have normal operation and when on L2 you would have constant on.

Make sense?

In the event that your system is wired exactly as shown in the top panel of your diagram then its just a case of flipping the switch around. Com would now go to terminal 86, L1 would go to battery pos and L2 would go to the output on the sensor

PCRman wrote:I think he is talking about controlling a temp sensitive thermo without an air con at all.

Does the thermoswitch earth onto the block when the fan is active?

If it does then the sensor should be on the otherside of hte relay (ie between terminal 85 and the ground).

What you want then is a single pole double throw center off switch. that works like this.



you would put the switch between the sensor and the #85 on relay with COM connected to the relay. and then L2 would go to the sensor while L1 would be earthed.

That way with the switch in the off position you would have no fan at all, when running to L1 you would have normal operation and when on L2 you would have constant on.

Make sense?

In the event that your system is wired exactly as shown in the top panel of your diagram then its just a case of flipping the switch around. Com would now go to terminal 86, L1 would go to battery pos and L2 would go to the output on the sensor

Yep, that'll work too.

your best off running any type of switch off the negitive rather than positive

11_evl wrote:your best off running any type of switch off the negitive rather than positive

X2 (& less hassle if you already have a single wire switch)


...EDITED VERSIONS OF IMAGES...
Single wire earthing thermoswitch

Alternative version for thermofan switch (is like your diagram)

Hope it helps

All these diagrams stray from the original manufacturer's instructions diagram and is now getting confusing as far as I'm aware normally 85 is earth 86 is switch 87 is power out and 30 is power from the battery+ just how the original instructions are laid out don't want to stray from this incase the new thermo switch gets fryed but can you tell me if this will work ok? and if not why? and will I get reverse feed thru the thermo switch and kill it or do I need to add something?



Thanks Robb.

looks like it will work to me!
as for you back feeding the thermo switch, in that diagram it looks fine.
but I have not personally played with a thermo switch.

I cant see how you feed power back through the thermo switch as there is no circuit for power to travel back, unless like someone said if it is an earthed thermo switch.

I'd be interested in knowing what people mean by this
theotherleft seems to have an idea (maybe auto elec or electronics?)

ashley

BOGFROG wrote:All these diagrams stray from the original manufacturer's instructions diagram and is now getting confusing as far as I'm aware normally 85 is earth 86 is switch 87 is power out and 30 is power from the battery+ just how the original instructions are laid out don't want to stray from this incase the new thermo switch gets fryed but can you tell me if this will work ok? and if not why? and will I get reverse feed thru the thermo switch and kill it or do I need to add something?

Thanks Robb.

Your version looks fine and is essentially just what i have in the lower image (i just managed to needlessly over complicate the thermoswitch). the switches im used to are single wire jobs that basically earth the circuit when the temp reaches spec (bit like the temp guage sender but is either on or off, not variable resistance) . Just make sure that that SPDP switch goes in with the COM to ignition, one side to your override and the other to normal. Feedback shouldn't be a problem as long as the switch does not earth out.

An yeah i had 85 and 86 backward in both images and 30 and 87 in the second. sorry Ive updated the pics to be correct and in line for your system (the second image)

Just dont ever forget its in OFF after youve been working on the system or.... COOKED

Thanks PCR Man I thought it would be fine and then I read your diagram and got confused, but then thought to myself the pins on the relay we're the wrong way around! It was a simple mistake no stress.Thanks heaps for your help it's much appreciated Cheers Robb.

just realised my thermo fan spins the wrong way (it was mounted to the radiator when I got it ) so I didn't even check til i noticed the temp climbing even with thermo on. Can I just swap the wires around the other way on the fan to reverse the direction? Also it's mounted to the front of the radiator is this better or should I rear mount it? thanks in advance Robb.

"Will my fan work better as a push or pull fan"

Oh no .... can open ... worms everywhere...

I can really only come at this from my PC nerd side (don't have much engine cooling tech up my sleeves). You start to run into stuff like static pressure and air flow resistance and fluid dynamics and such like. Thats usually where i go looking for nurofen. Basically (as I understand it) if you have a pusher fan (mounted on the front of the radiator pushing air in there will be some pressure buildup between the fan and the radiator which will reduce airflow through the radiator. Unless you have a high static pressure fan (like I've got on my PC heatsinks) that moves the same amount of air at higher pressure differentials I would think that you would get better cooling with the fan mounted on the inside sucking air through the radiator.

Additionally having the fan on the inside would mean that at highway cruising speeds (where air ram puts more air through the radiator than a fan ever will) you will have a less impeded air path to the radiator.

Lastly my research indicates that having a puller (as opposed to pusher fan) may result in more even airflow through the section of radiator covered by fan/cowling.

My personal opinion is go with a puller fan. But I accept that others may have their own opinions. You will also make gains as far as the volume of air moved per unit time by making sure that the cowling is nice and snug agains the fan blades and that air can't get in other than through the radiator itself.

Also a DC motor should run fine in reverse polarity.

Hope it helps.

Thanks PCRman great advise! The fan is obviously a (puller fan) it's just been mounted on the wrong side of the radiator by the previous owner so just a matter of swaping sides that will work much better thank you again!
Robb.