Radiator Fan ....... "turn off" Switch

[nikojo]

My question ...... can a switch be placed that can control this?? Where and how would you splice in the 24V to disengage the solenoid/fan?


The fan engages via the cadillac solenoid when it does NOT get 24V ....... by default if there is a fault/failure in sensor, the lack of 24V engages the solenoid/fan. If the solenoid gets 24V is disengages the fan.

I also understand the time delay module that allows acclerator to temporarily disengage for temporary power and also initial fording.


I understand this may not have much of an application but wanted to know if it can be done.

 

[Coug]

yes, all you would have to do is wire to a 24V source then to the hot side of the cadillac valve wires. Would be a relatively easy/straightforward wiring job.

 

[frauhansen]

I believe there was a way to disable the fan. For example, for a water crossing. But I can't remember what it was.
But I think someone mentioned it here:

(I'm on the road right now and can't listen to it)

And there is a YT Video about a manual OFF-switch it:

 

[papakb]

nikojo, years back before I took the time to understand how the fan system worked ( and parts were less available) I wired in a DPDT switch to my truck that performs 3 functions. Always on, always off, or automatic (normal) mode. It's simple to do and all it takes is a couple of connections to the time delay relay 4 pin connection. I salvages a connector from an old Ford mustang in a salvage yard and wired it in. Works fine but is now left in AUTO mode since I fixed the fan.

frauhansen, just stomp on the accelerator and the switch on the side of the IP triggers the time delay relay to disconnect the fan for 10-20 seconds to allow the fan to freewheel when entering the water for fording. What I did was a hardwired version of that. Guten tag.

 

[nikojo]

nikojo, years back before I took the time to understand how the fan system worked ( and parts were less available) I wired in a DPDT switch to my truck that performs 3 functions. Always on, always off, or automatic (normal) mode. It's simple to do and all it takes is a couple of connections to the time delay relay 4 pin connection. I salvages a connector from an old Ford mustang in a salvage yard and wired it in. Works fine but is now left in AUTO mode since I fixed the fan.

frauhansen, just stomp on the accelerator and the switch on the side of the IP triggers the time delay relay to disconnect the fan for 10-20 seconds to allow the fan to freewheel when entering the water for fording. What I did was a hardwired version of that. Guten tag.

Great suggestion! Love that. Just have to remember to turn it back 'on' or 'auto' and not accidentally leave it off.

 

[midnightshadow]

Ok I've been pondering this idea as well. My idea is(and big question) can I splice a wire into the fan cut off temp censors wires 1 of them. To a switch. My thought behind this is if the switch is off fan will run as normal operating Temps. If switch is on fan will run all the time essentially system thinks it's not working and makes fan always run. Basically what I'm after is I really don't like the motor running as hot as it does. I know this is normal 215 I think it comes on. Hopefully this makes sense. But here is the next question how heavy of a swich does it need 2 be. I do have a halo type amps test but thought I'd just ask any way

 

[Coug]

Ok I've been pondering this idea as well. My idea is(and big question) can I splice a wire into the fan cut off temp censors wires 1 of them. To a switch. My thought behind this is if the switch is off fan will run as normal operating Temps. If switch is on fan will run all the time essentially system thinks it's not working and makes fan always run. Basically what I'm after is I really don't like the motor running as hot as it does. I know this is normal 215 I think it comes on. Hopefully this makes sense. But here is the next question how heavy of a swich does it need 2 be. I do have a halo type amps test but thought I'd just ask any way

Yes, you can wire in a switch. All you need to do is interrupt the power to the cadillac valve, so if you want to do it at the thermoswitch circuit, or right at the cadillac valve, it should work the same (though if the TDM fails it can prevent the fan from engaging, so at the cadillac valve would be the surrest bet)

Doesn't have to be a very hefty switch. I would think a 10 amp rated switch would be more than enough

 

[midnightshadow]

Yes, you can wire in a switch. All you need to do is interrupt the power to the cadillac valve, so if you want to do it at the thermoswitch circuit, or right at the cadillac valve, it should work the same (though if the TDM fails it can prevent the fan from engaging, so at the cadillac valve would be the surrest bet)

Doesn't have to be a very hefty switch. I would think a 10 amp rated switch would be more than enough

So splice into 1 wire, + or - dies it matter. Also to be safe your talking the 2 wires between Cadillac valve and TDM .


Ok, , if the TDM fails this causes the fan to not work. Does this happen during normal conditions, or just because of the way I was thinking about wiring in a switch in my original plan. My understanding of the system was that if anything failed fan always ran. My idea behind the fan switch, is that no matter what position the switch is in on or off the fan will run when it has to or just all the time idiot proff. Thanks for reply

 

[Autonomy_Lost]

So splice into 1 wire, + or - dies it matter. Also to be safe your talking the 2 wires between Cadillac valve and TDM .


Ok, , if the TDM fails this causes the fan to not work. Does this happen during normal conditions, or just because of the way I was thinking about wiring in a switch in my original plan. My understanding of the system was that if anything failed fan always ran. My idea behind the fan switch, is that no matter what position the switch is in on or off the fan will run when it has to or just all the time idiot proff. Thanks for reply

I would interupt the positive, not the negative. Otherwise it might be able to "find" a ground somewhere.

The TDM in theory could fail either open or closed, meaning the fan could be stuck on or stuck off. I'm not sure which is more likely.

The cadillac valve could also fail open or closed.

However, if the failure is simply loss of voltage or hydraulic pressure, the fan will be on.

 

[Mogman]

I would simply wire a switch in line with the temp switch, ether wire will do, interrupt that wire (open) and the fan will run.
This can be done with a couple Packard connectors so no permanent modification would be needed.

 

[Coug]

So splice into 1 wire, + or - dies it matter. Also to be safe your talking the 2 wires between Cadillac valve and TDM .


Ok, , if the TDM fails this causes the fan to not work. Does this happen during normal conditions, or just because of the way I was thinking about wiring in a switch in my original plan. My understanding of the system was that if anything failed fan always ran. My idea behind the fan switch, is that no matter what position the switch is in on or off the fan will run when it has to or just all the time idiot proff. Thanks for reply

Yes, the 2 wires going to the cadillac valve from the TDM. As mentioned above, doing the positive wire is better as it kills power to the valve.


Normally, yes, most things that would cause a failure of the fan circuit will leave the cadillac valve without power, and therefore the fan engaged.
There are 2 things that can fail and leave the fan system disabled, but if you know it's messed up you can override it.

The TDM can fail so that the cadillac valve is getting power through the fording interrupt circuit (if you don't know, the purpose of the TDM is to allow the fan to be disengaged for 15-20 seconds by pushing the accelerator pedal to full throttle briefly, for when you are going fording through deep water the fan will not be powered when hitting the water, as that tends to destroy the fan blades. Also frees up a little engine power in case of emergency/panic situation, because the fan takes a lot of power. Some estimates have it at 10hp or more)

The thermoswitch can fail in the hot/live/shorted position, so that even if the engine is too hot, power still goes through it, thus disabling the fan.

(I normally hate auto-correct, but for "thermoswitch" it's replacement suggestion was "thermos witch" and that's kind of amusing)

 

[nikojo]

The thermoswitch can fail in the hot/live/shorted position, so that even if the engine is too hot, power still goes through it, thus disabling the fan.

I think you meant if the thermoswitch fails it will still provide power and will ENABLE fan not disable.

Correct me if wrong as I need to understand this circuit.

 

[Autonomy_Lost]

I think you meant if the thermoswitch fails it will still provide power and will ENABLE fan not disable.

Correct me if wrong as I need to understand this circuit.

If power is applied to the cadillac valve, the fan will be disabled.

 

[Mogman]

If power is applied to the cadillac valve, the fan will be disabled.

When the thermo switch is open the fan is enabled, it is a failsafe system, anything that disrupts power to the cadillac valve turns the fan on, complete the circuit and the fan "stops"
The the thermo switch is normally closed, means it opens when it gets hot.

 

[Coug]

I think you meant if the thermoswitch fails it will still provide power and will ENABLE fan not disable.

Correct me if wrong as I need to understand this circuit.

If the thermoswitch fails and is energizing the circuit, then it disables the fan. When there is no power through the circuit, the fan is engaged.

In other words, applying power through the switch turns ON the cadillac valve, which in turn disables engine power to the fan (fan still spinds some due to drag inside the fan clutch, but not with anywhere near as much force as when it's engaged)

 

[nikojo]

If the thermoswitch fails and is energizing the circuit, then it disables the fan. When there is no power through the circuit, the fan is engaged.

In other words, applying power through the switch turns ON the cadillac valve, which in turn disables engine power to the fan (fan still spinds some due to drag inside the fan clutch, but not with anywhere near as much force as when it's engaged)

If the thermoswitch fails.......the failsafe is to de-energize the circuit and ENABLE the fan.

That's my understanding about it's design, ie if any sensor/wiring fails it results in de-energizing the valve and thereby enabling the fan.

Maybe I'm misunderstanding what the word 'fail' means or what is the thermoswitch.

I'm thinking the thermoswitch is the temp sensor and is a switch that is normally 'closed' therby completing circuit, energizing the valve, and disabling the fan.
When the temperature reaches threshold the switch 'opens' and the circuit is cut off, de-energizing the valve, and enabling the fan.

If the switch 'fails' it is 'open' and circuit is cut off, and valve is off, and fan is enabled.

 

[Autonomy_Lost]

Switches, sensors, valves, etc, can all fail in either the open or closed position. There is no guarantee that a failure will result in the fan being on. The system was designed such that the most LIKELY failure results in the fan being on.

Edit: think of it like air brakes on a semi truck. If you lose air pressure, the brakes apply. That covers you if you lose an air line. However, there is still a possibility of the brakes failing if for example you have a problem with the brake pedal itself.

 

[Coug]

If the thermoswitch fails.......the failsafe is to de-energize the circuit and ENABLE the fan.

That's my understanding about it's design, ie if any sensor/wiring fails it results in de-energizing the valve and thereby enabling the fan.

Maybe I'm misunderstanding what the word 'fail' means or what is the thermoswitch.

I'm thinking the thermoswitch is the temp sensor and is a switch that is normally 'closed' therby completing circuit, energizing the valve, and disabling the fan.
When the temperature reaches threshold the switch 'opens' and the circuit is cut off, de-energizing the valve, and enabling the fan.

If the switch 'fails' it is 'open' and circuit is cut off, and valve is off, and fan is enabled.

As was mentioned, any electrical component can fail in either an energized or deenergized position.

If it fails closed, then power will be flowing through it all the time.

If it fails open, then no power will flow.


Also to mention, the TDM can fail while energized, thus preventing the fan from being engaged. This happened to me, and engine temp was 240 when I noticed.
Unplugged the cadillac valve, and fan was on until I fixed the issue.

So to reiterate, there are 2 sources of power that go to the cadillac valve in order to disengage the fan (thermoswitch and TDM). If either of them fails in the closed position, the fan will never come on. Therefore the ONLY way to make sure the fan WILL engage if you are wiring in a separate switch, is to do it at the cadillac valve itself.

 

[nikojo]

As was mentioned, any electrical component can fail in either an energized or deenergized position.

If it fails closed, then power will be flowing through it all the time.

If it fails open, then no power will flow.


Also to mention, the TDM can fail while energized, thus preventing the fan from being engaged. This happened to me, and engine temp was 240 when I noticed.
Unplugged the cadillac valve, and fan was on until I fixed the issue.

So to reiterate, there are 2 sources of power that go to the cadillac valve in order to disengage the fan (thermoswitch and TDM). If either of them fails in the closed position, the fan will never come on. Therefore the ONLY way to make sure the fan WILL engage if you are wiring in a separate switch, is to do it at the cadillac valve itself.

I did not know this.........I always assumed it could only fail closed.

Thank you.

 

[midnightshadow]

Ok wow, so are we still on the concensus. That the switch should be wired in between cadillac valve and tdm.