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.
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 (https://www.foreforums.com/index.php?topic=44232)
Wax vs Electronic Radiator Fan Controller (https://www.foreforums.com/index.php?topic=44280)
Thermo Valve Conversion Kit (https://www.foreforums.com/index.php?topic=34513)
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.
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
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.
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.
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.
Normally the fans go to high speed at 190 degrees water temperature.
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.
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.
Thanks for the heads up on the tachometer sensor, sounds useful for many things.
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?
Sounds about right to me, but what do I know
At idle it is hard to hear it ramp up as the faster the engine turns over the faster the fans go.
Ha, probably more than me 😛
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 (https://www.foreforums.com/index.php?topic=41024.0)
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.
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. 👍👍
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.
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.
I don't know the answer to your question but I think you would want them to be running even when engine it too cool so the CAC could be cooled down.
Yes, even when coolant doesn't require fan speed, there must be air flow over the CAC.
So, think of this is LOW-HIGH, not OFF-ON.
Ok got it, just checked mine and it appears to be stuck on high. I only say that because when i disconnect the controller it doesn't seem to change speed...may need to purchase one of those tachometer devices to know for sure but it doesn't seem to get loud or blow more air when i disconnect.
There could also be the situation where I'm using the Napa sensor and not the Danfoss...but who knows.
Dylan, I do know to hear your cooling fans on high while your parked you need to have the high idle switch ON. Jim.
I did not know that...and of course, my high idle/cruise is not working right now 😡
So Dyran you too have a failed electronic controller. Fails to the fans running fast position. The wax valve has infinite rpm ranges, not hi and low. Just as required. I certainly can hear my fans ramp up at a low idle from the drivers seat with my added solenoid commanding max speed by shutting off sense control pressure. I run a standard thermostat and the hi temp wax valve. I also run my background fan speed so low that the fans just turn prior to warming up. This will cause hi IAT which I've rairly see and I either reduce power settings or manually ramp fans up. There is a adjustment inside the wax valve that can be set but the manufacturer recommends they do it. Wonder lodge and blue bird use a additional IAT sensor and solenoid to manage cold engine hi IAT Issue. I had given consideration to this but never needed to add. I actually have a needle valve inline to the solenoid if I desire higher background speed but haven used except to increase fan speed too just turning so as to keep warm oil in motors and not damage bearing from setting in one position. Needle valve was also my safety blanket to command fans to max speed to get home if I had a issue. Suspenders and belt mentality.
Scott
Please explain:"solenoid that closes
every brake application and when the retarder is applied"
Where is the solenoid valve placed?
Thanks Tim
So the solenoid was added in the fans speed pressure reference line. Restriction in this line causes the fan speed to increase to max. No restriction causes the fans to actually stop turning. So with the increase of temperature the restriction in the valve closes and increases fan speed. Wax valve or electronic controller. The added solenoid was added for several purposes. Extra cooling, extra dynamic braking, and yes I can feel and hear the extra drag when engaged. A way to dump all the extra heat I normally ignore but like to be able to stop and sleep in the bedroom without cooking for a hour. I drop 25 degrees off the top of my engine and transmission temperature compared to my normal OTR temps. I have increased MY normal OTR temps to about 200 and in doing so burn less fuel for cooling. I have a three position switch which is fan override OFF (this is basically what everyone has on there coach stock, fan override ON, and fan override in AUTO Fans go to hi speed during brake application and retarder use. Eventually I will add a time delay off switch to keep the fans running a additional time after they no longer are requested. Not needed but would like.
So driving down the road normally in AUTO. 30 minutes before shutdown I like to go to ON position to dump heat. Yes it costs more fuel but worth it to me.
Note, after I initially installed the wax valve is when I recognized how nice it was prior with fans on hi to sleep quickly, much cooler. Also saw much higher retarder temperature. So when we use our coach it may stay running across the states with minimal overnight stops. Huge difference.
Scott
Wanted to hit on this topic again...
Today I was fiddling with my fans again. Noticed that the connector leaving the controller was green with corrosion on the pins. I cleaned them up the best I could and started the process below:
To circle back to the discussion of testing the fans by unplugging the controller while idling...I thought a good test would be to start up engine, unplug controller and then see if I notice the fans change RPM. If they ramped up, then the thought was the controller is working...but then someone mentioned in this thread that the high idle needed to be on for the fans to kick up and it wasn't until today that I tested that out. (My cruise control/high idle is still not working 100% so testing anything on high idle is hit and miss)
...so what actually happened is when the high idle is on the fans are definitely at a higher RPM than when at normal idle RPM. Unplugging the controller did nothing at either RPM. So normal idle, fans on lower RPM, unplug controller, nothing changes. High idle, fans kick up, unplug controller, nothing changes.
Are my fans working correctly?
I keep hearing people say that they can hear their fans kick up to higher RPM while driving but I've never heard that, seems to be too much other noise for me. Maybe if the passenger window was open and I was in a tunnel maybe i would hear it?
Maybe my rig is running so awesome it never needs the fans to ramp up to full RPM because it run so cool. (I know, impossible)
I'm not against installing the Wax valve and abandoning the electric controller but don't want to if I don't have to...for now anyway, too many other projects.