Hi,

The hydraulic cooling fan gets signal from ECU which collects data from engine temperature, transmission fluid temperature, outside temperature and battery temperature sensor combined.
And starts cooling gradually when needed. On idle it spins like you can easily stop by hand. (It should spin all the way). When AC is engaged the fan spins on max rpm regardless engine temperature.

When you disconnect the socket from ECU, the fan must start 100% spinning on engine running at idle. If not, the solenoid (which restricts the hydraulic flow) seems to be bad.
When you run AC on coldest but the fan does not spin high, Or when you disconnect the engine temperature socket but the fan does not spin high then the fault seems to be from the ECU signal.
To be sure from the solenoid failure you can hold and try to feel the opening of the solenoid by hand also.

Also you can diagnose fan spinning speed via DRB hand terminal. It has a menu where you can engage the fan between 1% to 100% gradually.

Hope you can diagnose your problem.

Regards.

(English is not my native language, please forgive errors.)

 

Erem, I saw no errors at all in your English speaking so I say very much respect for that as it is not your native language .

Phit

 

Thank you for your help!

So, am I understanding this correctly...If I dis-connect either connector going to the hydraulic fan unit - either the one at the bottom going to the solenoid or the one on the side going to the temperature sensor - the fan should spin by itself at that point?

Thanks again very much for your help!

 

It's much easier to test the hydraulic fan by pulling the coolant temp sensor plug off of the coolant temp sensor with the engine running.

If the fan itself is functional it should automatically kick the fan on to its' highest speed, regardless of engine temp. If the fan is still DOA, then it's likely a problem with the fan solenoid, which can be replaced however you will have to source a Ford part for it as Mopar does not sell the solenoid separately and, if they're still available, complete fans were around $800 from the dealer.

You can do a search here to find the Ford part number needed for the solenoid, there's a rather lengthy thread on it from a couple years ago.

If you pull the coolant temp sensor and the fan spins up, then it sounds like you may have a problem with the ECM commanding the fan to turn on, which could be any number of issues but I'd start by replacing the coolant temp sensor first if that were the case.

 

Thanks so much for the help so far Folks!

Today I opened the hood of the Grand Cherokee and started up the motor, and observed that the fan was spinning at a slow speed. When I turned on the AC full blast with the engine at idle in the driveway the fan did NOT speed up at all. So at least the fan is not bad...

If I understand everybody correctly my next step will be to dis-connect the temp sender located on the upper right hand side of the radiator, right?

If the fan speeds up then the temp sender is bad, if not then what?

Thanks again everybody!

D.

 

While the ECT (engine coolant temp sensor) in on the thermostat housing on the 4.0 I6 the ECT on your 04 4.7 it should be on the front of the intake manifold. It's down in there and believe it's between the alternator and AC compressor. Unplug the connector as Jeeples mentioned and see if your fan speed switches to high while running which it should. If it does run at high speed with sensor disconnected change out the ECT.

You can also check for fault codes and often if the hydraulic fan solenoid is bad it may throw code 1499.

On a separate subject which shouldn't cause your fan to not run at full speed has to do with power steering fluid specs. When you pulled the fluid out of your power steering pump reservoir was the fluid color amber? And was the $20 bottle of fluid you bought from the dealer red? If so you have ATF+4 red transmission fluid mixed with true OE amber colored power steering fluid which isn't good.

Mopar doesn't even make the MS5931 amber OE fluid anymore and they now they sell the MS9602 ATF+4 as power steering fluid as a replacement when it's really transmission fluid. Read the below info in the middle of the page on "Power Steering Fluid".

http://www.wjjeeps.com/service/maintenance_wj.htm

Valvoline makes a power steering fluid which is the amber MS5931 spec and some house brand part store fluids also meets this spec. Know it's a waste of money but I'd get that red ATF+4 fluid out of there.

I have the same 04 4.7 you do and have a couple gals of the Valvoline PS fluid and I'm going to change all the old OE fluid out of the hydraulic fan/power steering system. Likely just one gallon would do the job. And you do want to turn the power steering from clock to clock to get the air out of the system which you found out after the fact. Good luck.

 

The newer 3 wire plastic solenoid is or was available at the last I checked. The older 2 wire metal one will need to come from ford.

To me if you remove the ECT connector and your fan starts running in airplane mode you may just have dirt in the system. And that easy. Let it run in airplane mode 5-10min and then shut off engine and remove the lowest return line on the PS pumps tank and drain it and put fresh fluid in. I also use the valvoline. It's worked for a few other members. I have a magnet hanging in the fluid to attract ware metals.

The AC on and fan not spinning may mean you low on charge. Pulling the ECT connector will force the PCM to put 12v on the fan solenoid.

 

Wow! Everybody is very helpful here! Thanks thanks thanks for all the help so far!

Today I located the engine coolant temp sender in the upper front middle of the block between the AC and Alternator. I wiggled the connector around a bit and finally got it off, but the exterior part of the female part of the plug housing kind of broke a bit and one side of the plastic housing fell into the bowels of the engine.

Anyway, with the ECT sensor wire dis-connected I started the engine up and the fan began running like a freight train - at full speed. Those who say it sounds like an aircraft propeller at takeoff are right!

Also, the MIL light for engine lit up and stayed lit whilst I was dicking around with this procedure today.

I plugged the ECT wire back into the sender and started the engine and the MIL in the dash went out and the fan went back to slow running. The engine was at operating temperature by the time I did this...and the fan should have been turning faster, yes?

So Folks, what should I do now? Get a new ECT sending unit from (gulp) the Stealership?

Also, I found the bottle of MOPAR steering fluid rattling around in the back of the Heep and checked it for color - it is amber. Many thanks for the tip on the Valvoline amber colored product, I will go out and get some!

Thanks again everybody!

D.

 

It sounds like it is properly working. When was the last time you replaced thermostat? When was last time you flushed inside and in front of radiator?

 

I confess I have never replaced the thermostat. The vehicle has 150,000 miles on it and I am the original owner from new. I used to have the Stealership replace all the fluids every 2 years, so it has had fluids replaced on a fairly regular basis. I also had the Stealership replace the brake fluid every 3 years as well (I can't believe how many people never replace/renew their brake fluid on a regular basis - it is highly hygroscopic and sucks moisture out of the air like crazy and degrades pretty quickly once the process begins.

I did replace the radiator about 6 months/2500 miles ago when the original Factory unit exploded open in stop and go city traffic. Obviously I did not think the water pump and/or thermostat needed replacing at that time. When I had the old radiator out I thought about and tried to diagnose the water pump - I did the "water pump pulley" wiggle test and it didn't seem loose or sloppy - so I didn't replace the water pump and thermostat at the time.

I did of course replace the anti-freeze at the time of radiator replacement - I like to use Prestone ethylene glycol and distilled water so I put new fluid in with a pretty much 50/50 solution in the new radiator.

I did replace the water hoses at that time, and the radiator cap as well.

Could all of this be due to a malfunctioning thermostat?

D.

 

I did of course replace the anti-freeze at the time of radiator replacement - I like to use Prestone ethylene glycol and distilled water so I put new fluid in with a pretty much 50/50 solution in the new radiator.

I did replace the water hoses at that time, and the radiator cap as well.

Could all of this be due to a malfunctioning thermostat?

D.

You were posting at the same time I was. Lol.

Sounds like you've done a good job in replacing all your fluids and nice to see it's been well taken care of since new.

I use Prestone green antifreeze plus distilled water in all my other/past Jeeps. But next time you change it out flush all the Prestone antifreeze out of the system and install either Mopar or Zerex G-05 'HOAT' antifreeze plus 50% distilled water. It's a yellowish antifreeze and that's the spec as can be seen below under 'Cooling systems' for our WJ's.

http://www.wjjeeps.com/service/maintenance_wj.htm

I wouldn't think a bad thermostat would cause your hydraulic fan to always run low at idle speed. Now if you had a whole bunch of air trapped in the cooling system that could cause problems with the ECT but you'd also hear your heater core gurgling.

BTW, if you don't have a digital multi-meter they're cheap and you can pick one up for $20.

 

Do you have a multi-meter with an ohms setting? If so you may be able to do a resistance test on your ECT sensor to see if it's good. Set your meter to a mid-ohm setting and have the key off with ECT connector removed. Place the 2 meter probes on both contacts of the ETC and write down the meter reading. You should do this with the engine cold before starting then with the engine warm after running. You should see high resistance with the engine cold and a much lower resistance with the engine hot.

It's beyond me why they no longer have the resistance test chart for the ECT sensor in the WJ FSM's, at least I couldn't find one. Below is one on the TJ forum and this is the exact same one in all the ZJ FSM's. The ECT's should work the same way but don't hold me to those exact specs since they very well could be different for the WJ. And ignore the talk about IAT's in that thread/post and just look at the chart with temps/resistance.

http://www.jeepforum.com/forum/f9/normal-iat-sensor-reading-979267/#post8976533

Spec for a ZJ is the resistance shouldn't be less than 1340 ohms with engine warm or the ECT is likely bad. But again don't hold me to this spec and just look for large swings in resistance between cold vs hot coolant/engine.

Have you ever checked to see if you have a fault code for your ECT? That is before you disconnected that connector which may show up in the code history?

If your ETC is bad they may not cost as much as you think. But going to the dealer could be a whole different story.

The Mopar (OE# 56027873) ECT sensor for your 04 4.7 is $42 on Amazon with free shipping if you have prime or $45 on Rockauto plus shipping.

https://www.amazon.com/Mopar-56027873-Coolant-Temperature-Sensor/dp/B006DX0Z6W

Good deal you added the amber fluid and good luck.

 

You need a scanner that reads live data. A simple test for the ECT accuracy is to let the WJ sit over night and before starting read what the ECT and IAC say. The ECT should be within 10 degrees of ambient to be within spec. Same with the IAC.

Your cooling fan won't ramp up to a speed you'll notice until around 240 degrees.

 

That fan should always be spinning slow on a cold engine start. If it's not there is dirt clogging the solenoid or the bearings in the fan are shot.

Pulling the ECT connector and running the fan in airplane mode for a while will be your best way to try and flush the dirt out of the valve and hopefully get it somewhere where you can remove it.

 

A infrared temp gun should also be in your tool box. Then you can gun the upper coolant exit and compare it to your scanners temp.

 

If the ECT is unplugged long enough to test the fan, will it cause a code?

 

Yes the check engine light will come on. after its plugged back in, the light will go off.

 

86cj74.2L :: "Your cooling fan won't ramp up to a speed you'll notice until around 240 degrees."

Wow! Really? That makes no sense to me. Why would the system allow the engine to get that hot.

I put in a new radiator, thermo, hoses, fluid. It seems to have solved the leak, I hope hope hope.

Today it's 65 degrees. All around town it stays 195F all day long, steady as a rock, freeway, stop and go, mall parking lots, everywhere. But when I get close to home, hit the dirt road, and slow to 15-20MPH it heats up to 210F. Turned on the A/C to see what would happen - it went over 210. Is this normal?

Takes about 20 minutes on that dirt road slow driving to get home. It didn't get below 210. Seems the fan should EASILY be able to maintain 195. No?

Seems something is failing to speed up the fan. It should easily maintain 195. Something is wrong. If I modify the solenoid like in the video it will increase the fan speed throughout, but if whatever is supposed to speed up the fan isn't working, it will still get too hot in some circumstances.

Or is this normal? Why would it allow the engine to get above 195? Makes no sense.

Sorry - really frustrated with it.

 

210 is near normal operating temps and you shouldn't expect yours to stay at 195 under all circumstances. This is particular true if you're driving slow on dirt roads with the AC on and if it goes slightly over 210 it isn't going to hurt anything.

Speaking of dirt you may want to use a garden hose on your condenser and rad, along with between them, since they very well could be clogged some with dirt/dust. Don't use super high pressure which may damage the fins or these parts themselves.

 

I guess I'll live with it the way it is. Pulled a trailer yesterday. Went above 210 (215-220) and then fairly quickly went back to 195. Then above 210 again. Then back to 195. Cycled like this all the while. Coolant level was same when I looked this morning, so doesn't seem to be losing any. Maybe it's working as it should, though it seems too hot. But I guess that's the way it's engineered. Thanks everyone for the info.

 

When it gets to the 5/8 or 3/4 mark on the gauge, thats when its to hot!

 

Issue with cooling fan 01 4.7

So I also have been having an issue with my Hydro fan. Here are my symptoms.
My jeep runs at 199-205 consistently BUT when I shut it off to stop and get gas or run to a store ECT, I start it up and the temp slowly rises to 220-230 then after driving 5-10 mins it cools down to temp. I think I can hear the fan running but not sure at that time. I have done all that is discussed for troubleshooting as stated in previous discussions, Unplugged sensor and it goes into airplane mode, When the AC is on the fan runs, it also runs consistently at idle. Now last night I was checking things out and while in airplane mode the fan slows down a considerable amount (50% less) when I turn the wheels clock to clock but instantly recovers to full when I stop moving the wheel also the top pressure hose flexes a lot while doing this. I did install 2 new Power steering pumps last month, and a new thermostat. I hoping its not that again. Any Ideas?