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Topic: 2001 U320 Hydraulic Fan Functionality (Read 1543 times) previous topic - next topic

2001 U320 Hydraulic Fan Functionality

Been reading up on this but still don't have a good grasp on how the fans are supposed to function when working properly.

This is stemming from my other post on the mystery temp sensor. Looks like that sensor is for the hyd fan system not a second coolant sensor (I think). Before I figured that out I bought a temp sensor from Napa that had a part number that crossed referenced with a Cummins temp sensor part number. It looks very similar and has two wires so I installed it.
Because I'm dumb and I can't leave anything alone I attempted to disconnect and clean a ground wire that popped out of the same loom upstream from the sensor that was connected just below the valve cover on the passenger/rear side of the engine. It was corroded pretty bad and as suspected the bolt broke trying to remove it. I decided to relocate rather than extract broken bolt. It was at this time when I thought, hey I wonder if this ground has something to do with the fans. So I started the engine and touched the ground to the spot where the bolt broke and the fans turned off. So that led me to believe that the fans are off until the engine temp heats up (after research this is wrong I think)...but then when I reconnected the ground in its permanent new spot (which I tested by touching again) the fans stayed on and now I was confused. The new location is def a good ground but don't understand why when I touch the connector to the engine the fans stop but when I secured it properly the fans are on.

Ok, so like mentioned earlier I've been reading about this for a couple hours and what I gather so far is that It's normal for the fans to always be on...there's only 2 speeds correct? Low and high, they are never off while engine is running correct? Maybe when I was touching the ground to the block and it wasn't secured tightly the voltage was weird and turned the fans off?? Another thing I don't know is were the fans on high or low (obviously they should be on low if the system is working properly because engine was cold but not sure it is working properly)...I don't have nothing to compare it to (how loud the fans are on high vs low) because to be honest this is the first time I've really thought about if the fans are working properly...going on a year with this coach and haven't had any overheating issues.

So, since I just found the broken temp sensor (It wasn't all the way broke until I tugged on it so it could have been working properly but not sure) it's possible my fans have been running on high speed this whole time because it seems that if there any issues the fans will default to full speed.

More to the story...I was finally able to talk to parts guy at the mother ship today and he gave me a part number that was different than what I had found...probably because at this point I knew this was the fan temp sensor not the coolant sensor so that's what I told him to track down. He gave me a part number to a sensor from a company called Danfoss part number 1090173. Looks almost identical to the sensor I bought at Napa but maybe the internals are different so thinking I should grab that one but not sure.

I guess my question is, what's the best way to make sure the fans are working correctly? What is the correct order of events...example...fans on low until X degrees, fan back on low at X degrees, etc....
If everything is good then I won't order the Danfoss sensor and leave it as is.

Re: 2001 U320 Hydraulic Fan Functionality

Reply #1 –
Dylan and Aimee,

Keep looking around the Forum for old posts on the cooling fan system in your coach.  I know there have been many discussions about that system.  Different model years used different ways to control the fan speeds.  There are "wax capsule" mechanical controllers, and there are electronic controllers.  You need to determine which type is fitted to your engine.  Try different search terms and look through every hit that is returned.  Sometimes you need to do a lot of "digging" to find the exact post that will answer your questions.

One thing to be careful about when dealing with any kind of temperature switch: they can be either NO (normally open) or NC (normally closed).  They might look physically the same, but operate exactly opposite.  That's why determining the correct model number for your switch application is so important.

You can buy a inexpensive contactless RPM reader at Harbor Freight that will allow you to monitor the fan speeds.  I used one to check my fans after I rebuilt my hydraulic pump.

https://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html

Try the threads below for some possibly helpful info:

Fan RPM

Wax vs Electronic Radiator Fan Controller

Thermo Valve Conversion Kit

Re: 2001 U320 Hydraulic Fan Functionality

Reply #2 –
That is why you have that sensor there and I don't. I have the wax fan controller. Scott had the
electronic controller and he changed it to the wax controller and he added a manual controller
that I copied. 

Re: 2001 U320 Hydraulic Fan Functionality

Reply #3 –
When my electronic fan controller malfunctioned, I asked FOT for some information on the fan controller and sensors. FOT sent me these technical bulletins. I can't tell you these will apply to your coach but they may be helpful to you.
Regards,
Bob 

Re: 2001 U320 Hydraulic Fan Functionality

Reply #4 –
We replaced the electric controller with the wax controller.  The kit came with a small orifice that was missed on the initial install.  Its purpose was to keep the fans moving at a low speed until the coolant reached a temperature (180 degrees) to fully open the valve and ramp the fan up to hi speed.

Without the fans running low when cold, if we loaded the engine too much before the fans kicked in, the intake manifold temperature would rise to a point that it threw a warning.  When we put the orifice in after consulting with the manufacturer, problem solved.

So, long and the short, your assumption that fans either should run low or high seems correct.  180 degrees is the cut-on for high speed and that's been working flawlessly in keeping the coolant and manifold temps where they should be.

As a side note, Keith Risch told me by fixing the fan speed so it wasn't running high all the time we'd save a MPG or so.  That has proven to be the case so its definitely been worth the cost of replacing the no-longer-made electronic control module with the wax valve.

Re: 2001 U320 Hydraulic Fan Functionality

Reply #5 –
Quote from: Joe Phebus –
  180 degrees is the cut-on for high speed and that's been working flawlessly in keeping the coolant and manifold temps where they should be.

Hopefully, that is NOT how it works.

You want the the coolant temperature to get high enough that the thermostat is completely open plus a few degrees BEFORE the fans go to high.

180 degrees is below thermostat full-open and would waste a lot of fuel and HP if the fan is on high, as it would be running at full speed virtually all the time you are driving after initial warmup.

Re: 2001 U320 Hydraulic Fan Functionality

Reply #6 –
My fan controller use to open at 190 degrees but I wanted the engine to run at 190 so I put a
190 degree thermostat in the engine and then put in a 210 fan controller. Only once 2 years ago
the engine temperature went up to 200 degrees climbing a grade and I shifted down a gear and
the temperature dropped down quickly.

Re: 2001 U320 Hydraulic Fan Functionality

Reply #7 –
Normally the fans go to high speed at 190  degrees water temperature.

Re: 2001 U320 Hydraulic Fan Functionality

Reply #8 –
Quote from: wolfe10 –
Hopefully, that is NOT how it works.

You want the the coolant temperature to get high enough that the thermostat is completely open plus a few degrees BEFORE the fans go to high.

180 degrees is below thermostat full-open and would waste a lot of fuel and HP if the fan is on high, as it would be running at full speed virtually all the time you are driving after initial warmup.


I could be judging it wrong, Brett.  But my observation is just after we hit 180 degree, I see a drop in temperature,  Perhaps I'm mistaking the fans ramping up for the thermostat opening full and cooling the manifold temperature.  If that's the case, how would I know at what point the fans ramp up to high? 

Wax valve was from Source Engineering and seems a popular solution for RV owners.  Maybe I just need to give them a call again to find out, unless someone else here knows the default setting.

Re: 2001 U320 Hydraulic Fan Functionality

Reply #9 –
It probably is just the thermostat fully opening. I believe source engineering makes a 200 degree
controller and I would have used it but I could get the 210 one for more than half the price from
England. The only way I can hear if the fan has ramped up is by opening the bed or from outside.

Re: 2001 U320 Hydraulic Fan Functionality

Reply #10 –
Quote from: Chuck & Jeannie –
Dylan and Aimee,

Keep looking around the Forum for old posts on the cooling fan system in your coach.  I know there have been many discussions about that system.  Different model years used different ways to control the fan speeds.  There are "wax capsule" mechanical controllers, and there are electronic controllers.  You need to determine which type is fitted to your engine.  Try different search terms and look through every hit that is returned.  Sometimes you need to do a lot of "digging" to find the exact post that will answer your questions.

One thing to be careful about when dealing with any kind of temperature switch: they can be either NO (normally open) or NC (normally closed).  They might look physically the same, but operate exactly opposite.  That's why determining the correct model number for your switch application is so important.

You can buy a inexpensive contactless RPM reader at Harbor Freight that will allow you to monitor the fan speeds.  I used one to check my fans after I rebuilt my hydraulic pump.

https://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html

Try the threads below for some possibly helpful info:

Fan RPM

Wax vs Electronic Radiator Fan Controller

Thermo Valve Conversion Kit


Thanks for the heads up on the tachometer sensor, sounds useful for many things.

Re: 2001 U320 Hydraulic Fan Functionality

Reply #11 –
After more reading I'm going to check the low vs high speed functionality.
I have the electronic controller not a wax...

So if working correctly I should:

1. Start cold engine and see fans running. (Low speed)
2. Disconnect the electronic controller sitting on the frame in the engine bay
3. The fans should kick up higher after disconnecting the controller
I'm assuming I should be able to hear the fans kick up since I'll be close to them

Am I missing something?

Re: 2001 U320 Hydraulic Fan Functionality

Reply #12 –
Sounds about right to me, but what do I know

Re: 2001 U320 Hydraulic Fan Functionality

Reply #13 –
At idle it is hard to hear it ramp up as the faster the engine turns over the faster the fans go.

Re: 2001 U320 Hydraulic Fan Functionality

Reply #15 –
Quote from: dlkj07 –
After more reading I'm going to check the low vs high speed functionality.
I have the electronic controller not a wax...

So if working correctly I should:

1. Start cold engine and see fans running. (Low speed)
2. Disconnect the electronic controller sitting on the frame in the engine bay
3. The fans should kick up higher after disconnecting the controller
I'm assuming I should be able to hear the fans kick up since I'll be close to them

Am I missing something?
That is correct. I added a solenoid that closes every brake application and when the retarder is applied also manually as desired.  I can easily hear the fans ramp up or down drop from the drivers seat. If your electronic controller has failed I wouldn't spend money on replacement. I would change to the wax valve control system.
Hydraulic fan controller DIY
Scott

Re: 2001 U320 Hydraulic Fan Functionality

Reply #16 –
Quote from: dsd –
That is correct. I added a solenoid that closes every brake application and when the retarder is applied also manually as desired.  I can easily hear the fans ramp up or down drop from the drivers seat. If your electronic controller has failed I wouldn't spend money on replacement. I would change to the wax valve control system.
Hydraulic fan controller DIY
Scott
Thanks Scott, I read all your post about your conversion a couple days ago. If my controller is working fine I might do what you suggest and add the solenoid shut off valve to the electronic system, though I'd need to pick your brain more about how you set it up. I like the idea of fans at 100% during braking and retarder use. Did you ever install the delay timer for that? Also, not sure if you ever posted the wiring diagram of your setup but I would be interested...even if it's just a basic schematic. Thanks for making my brain work...or maybe I shouldn't thank you...it  cost me money.

Re: 2001 U320 Hydraulic Fan Functionality

Reply #17 –
If your controller is working correct it is the most desirable IMO. covers All the basics. Extra solenoid for dynamic braking and extra cooling prior to shutdown makes sleeping better quicker. 👍👍

Re: 2001 U320 Hydraulic Fan Functionality

Reply #18 –
Are the fans supposed to spin up instantly on a cold start? Or is there a delay or a minimum temp that needs to be reached before they fire up?

Really wish I could find a flow chart somewhere that explains the fan functionality from start up to shut down for the electronic controller setup.

Re: 2001 U320 Hydraulic Fan Functionality

Reply #19 –
I imagine the electronic control works the same as the wax control. When the engines starts up
the fans start up. As the engine revs up the fans rev up. The fans stay on low speed until the
coolant temperature gets to the set point of the controller and then the fans go into high speed.
I believe the temperature for that is usually 190 degrees. In high speed the fans will change speed
with the engines speed also. When the temperature drops below 190 the fans will go back to
low speed. When the engine shuts off the fans shut off.