Cooling issues

[Dpas1973]

Ok maybe someone has some insight I’m having a weird problem. To start my fan clutch moves in and out with my air compressor hooked up to the can shroud. I have replaced 2 Cadillac valves,time delay,water crossover sensor and 2 thermostats and the hoses from the Cadillac valve and the fan stays engaged as soon as I turn the truck on temperature never gets over 185. But the fan clutch works with compressed air. Does the fan sensitivity switch have anything to do with the fan staying on? Only part besides the power steering pump I haven’t changed? The power steering works fine no squeals or anything. Any insight is appreciated

 

[Milcommoguy]

What is the fan sensitivity switch? Guessing you're missing 24 volt to the temp switch or wrong switch. Connect those two leads together and fan should disengage.

Could be a BO kick down switch circuit too. Loss of power or any plug disconnect or module failure ... fan will run. Default mode, fan runs.

What transmission do you have? And are these parts known good? A little more info please...

Look here for prints> First chapter... https://gear-report.com/wp-content/uploads/2017/03/HMMWV A1 Troubleshooting.pdf

And it's snowing, CAMO

 

[Dpas1973]

What is the fan sensitivity switch? Guessing you're missing 24 volt to the temp switch or wrong switch. Connect those two leads together and fan should disengage.

Could be a BO kick down switch circuit too. Loss of power or any plug disconnect or module failure ... fan will run. Default mode, fan runs.

What transmission do you have? And are these parts known good? A little more info please...

Look here for prints> First chapter... https://gear-report.com/wp-content/uploads/2017/03/HMMWV A1 Troubleshooting.pdf

And it's snowing, CAMO

1123 4l80 I Jumped the temp switch nothing? Yea the kickdown switch can’t find anything about it online. Figured maybe that’s why it’s staying engaged all the time. And I have 24 to the temp switch and to the time delay when I unplug time delay the hissing from the Cadillac valve stops.


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[Mogman]

Have you made sure the clutch disengages (try and move the fan?) when you put air to it? I am not sure moving in and out is an absolute test.
If the "hissing" stops then I would say the cadillac valve is switching so I would look at that clutch again

 

[Dpas1973]

Have you made sure the clutch disengages (try and move the fan?) when you put air to it? I am not sure moving in and out is an absolute test.
If the "hissing" stops then I would say the cadillac valve is switching so I would look at that clutch again

Yes it free spins when I turn it with my compressor hooked up. This is crazy lol. I did not look at what the pressure was set on the compressor though.


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[Dpas1973]

Have you made sure the clutch disengages (try and move the fan?) when you put air to it? I am not sure moving in and out is an absolute test.
If the "hissing" stops then I would say the cadillac valve is switching so I would look at that clutch again

What’s the chances of a power steering pump not putting out the proper 90 psi for the fan clutch. I did not have a gauge to test the hose pressure going to fan shroud


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[Mogman]

What’s the chances of a power steering pump not putting out the proper 90 psi for the fan clutch. I did not have a gauge to test the hose pressure going to fan shroud


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Not too likely if the power steering and power brakes work.

 

[Dpas1973]

Not too likely if the power steering and power brakes work.

Yea so now what lol. I’m at a loss


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[Mogman]

You need to get the schematic and trace the signal, it is a fail safe system as pointed out above, just about any failure will cause the fan to run.

 

[Dpas1973]

You need to get the schematic and trace the signal, it is a fail safe system as pointed out above, just about any failure will cause the fan to run.

I understand but I have power to the Cadillac valve at all times so shouldn’t the system be good? If there what a problem wouldn’t I have no power and hissing sound to valve?


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[Milcommoguy]

Got to ask... Did it every work? Hoses connected to all the right places? Might be time to plumb in the test guage. Verify voltage to the Cadillac valve too, but you said change of state when unpluged... Soooo?????

Not even summer and starting the year off / on with fan problems. LOL

Chasing Cats and out of guesses, CAMO

 

[Dpas1973]

Got to ask... Did it every work? Hoses connected to all the right places? Might be time to plumb in the test guage. Might verify voltage to the Cadillac valve too.

Not even summer and starting the year off / on with fan problems. LOL

Chasing Cats and out of guesses, CAMO

I have had the truck 2.5 years and I don’t think it ever worked. I decided to fix this because it’s cold as hell here and it’s rough driving when the engine temp is only 150-170 degrees. Yes the valve is hooked up the correct way this is my second brand new kysor blue label Cadillac valve and like I said temp sensor blue tag and time delay all new lol. Only thing I have not done is cut in a gauge to measure pressure to the fan clutch. It’s just a weird one I guess.


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[Milcommoguy]

I have had the truck 2.5 years and I don’t think it ever worked. I decided to fix this because it’s cold as hell here and it’s rough driving when the engine temp is only 150-170 degrees. Yes the valve is hooked up the correct way this is my second brand new kysor blue label Cadillac valve and like I said temp sensor blue tag and time delay all new lol. Only thing I have not done is cut in a gauge to measure pressure to the fan clutch. It’s just a weird one I guess.


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Following the road you weave... I think the gauge will present data that is needed. The "I don’t think it ever worked" Sorta sends one off the trail of trouble shooting even after flipping all the parts with the good stuff.

Good luck finding some heat.

, CAMO

 

[papakb]

The only components in the fan system are the fan clutch, time delay relay, Cadillac valve, temp sensor on the crossover pipe and the switch on the injector pump. During nomal operation below 185 degrees the Cadillac valve is energized passing power steering fluid to the fan clutch to disengage it allowing the engine to come up to temperature. When the temp sensor sees the engine above 185 degrees it turns off the Cadillac valve , bypasses the steering fluid to allow the fan to engage to cool down the engine. This is backwards from the way a normal vehicle works. They say that you can stop the fan with an engine running but I think only a fool would try a stunt like that. They he'd replace the fan after he gets back from the hospital.

When the accelerator is floored it actuates the time delay relay and disengages the fan. This is done so when fording the fan isn't powered up when you enter the water snapping off the fan blades. I believe that in newer vehicles this is also done to give you extra power when the trans kicks down a gear.

In FAIL SAFE mode the fan clutch is engaged and runs all the time.

Testing with air will determine if the fan clutch is moving as it should and the only other real test is disconnection the connector(s) to the TDR which should also cause the fan to engage. This simulates the FAIL SAFE mode.

Most of this is common knowledge to us older HMMWV owners but it's important for the newcomers to understand since it goes against the way you think it should work.

 

[Dpas1973]

The only components in the fan system are the fan clutch, time delay relay, Cadillac valve, temp sensor on the crossover pipe and the switch on the injector pump. During nomal operation below 185 degrees the Cadillac valve is energized passing power steering fluid to the fan clutch to disengage it allowing the engine to come up to temperature. When the temp sensor sees the engine above 185 degrees it turns off the Cadillac valve , bypasses the steering fluid to allow the fan to engage to cool down the engine. This is backwards from the way a normal vehicle works. They say that you can stop the fan with an engine running but I think only a fool would try a stunt like that. They he'd replace the fan after he gets back from the hospital.

When the accelerator is floored it actuates the time delay relay and disengages the fan. This is done so when fording the fan isn't powered up when you enter the water snapping off the fan blades. I believe that in newer vehicles this is also done to give you extra power when the trans kicks down a gear.

In FAIL SAFE mode the fan clutch is engaged and runs all the time.

Testing with air will determine if the fan clutch is moving as it should and the only other real test is disconnection the connector(s) to the TDR which should also cause the fan to engage. This simulates the FAIL SAFE mode.

Most of this is common knowledge to us older HMMWV owners but it's important for the newcomers to understand since it goes against the way you think it should work.

I changed the parts 2nd Cadillac valve and fan still stays engaged. But if I hook my air compressor to the shrowd I can get it to free wheel


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[Mogman]

I changed the parts 2nd Cadillac valve and fan still stays engaged. But if I hook my air compressor to the shrowd I can get it to free wheel


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Then you need to get out the volt meter and see where the failure is.
The valve only has two wires 583 and 93 (according to the schematic I am looking at) if you have 24V across those two wires at the valve the fan should be cut off if not then it is not an electrical issue.
The fan will free wheel even when cut off but when the fan is engaged you can hear it roar when you rev the engine.

 

[SmartDrug]

Then you need to get out the volt meter and see where the failure is.
The valve only has two wires 583 and 93 (according to the schematic I am looking at) if you have 24V across those two wires at the valve the fan should be cut off if not then it is not an electrical issue.
The fan will free wheel even when cut off but when the fan is engaged you can hear it roar when you rev the engine.

This.


Worth noting - even if you're getting 24v to the wire, make sure they're making solid contact at the plug male/female (seated, dielectric grease, tight). I ran into a very similar issue, my fan was on full time, I was completely unaware as I was new to the vehicle, I couldn't figure out the issue, replaced everything, etc. What it turns out was doing it for me was a loose connection at the Cadillac valve defaulting to fan constant on, and a faulty coolant temperature sensor reading higher than actual. It took a lot of digging, replacing, and checking various components before I replaced the temp sensor/gauge with the updated one, flushed the coolant, and made sure the wiring was all up to snuff. No issues since, but a fair amount of head scratching getting to that point.

 

[Mogman]

This.


Worth noting - even if you're getting 24v to the wire, make sure they're making solid contact at the plug male/female (seated, dielectric grease, tight). I ran into a very similar issue, my fan was on full time, I was completely unaware as I was new to the vehicle, I couldn't figure out the issue, replaced everything, etc. What it turns out was doing it for me was a loose connection at the Cadillac valve defaulting to fan constant on, and a faulty coolant temperature sensor reading higher than actual. It took a lot of digging, replacing, and checking various components before I replaced the temp sensor/gauge with the updated one, flushed the coolant, and made sure the wiring was all up to snuff. No issues since, but a fair amount of head scratching getting to that point.

What I meant was to check to see if the wires to the valve had 24V, this would necessarily be on the valve side of the plug, use sharp probes to prick through the wire rubber coating.
I see time and time again where someone will unplug the connection to whatever and say they have voltage to whatever device they are testing, this means nothing, you are not testing the connection and you are not insuring that the circuit can carry the load, that voltage can drop to zip, zero, nada as soon as you plug it in.....

 

[Dpas1973]

What I meant was to check to see if the wires to the valve had 24V, this would necessarily be on the valve side of the plug, use sharp probes to prick through the wire rubber coating.
I see time and time again where someone will unplug the connection to whatever and say they have voltage to whatever device they are testing, this means nothing, you are not testing the connection and you are not insuring that the circuit can carry the load, that voltage can drop to zip, zero, nada as soon as you plug it in.....

I have voltage as soon as I disconnect the plug the valve stops hissing and lines go limp


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[Mogman]

I have voltage as soon as I disconnect the plug the valve stops hissing and lines go limp.

You should see the clutch go in and out as you do this just like with the air tests.
If the line going to the clutch goes limp then everything from the battery to the valve is working. as when the valve drops the pressure to the clutch it engages.
If the PS is working you definitely have enough pressure available and you say you have replaced the valve more than once.
At this point I would drop a gauge in that line to see how much pressure it has to release the clutch but you have replaced the valve more than once and that regulates how much pressure to put on the clutch.
Did you buy OEM valves or aftermarket? have you tried the original valve again?
You are right this is a strange issue.