Cooling Fan Thermo Valve

[RobRoy]

Source Engineering Inc | Custom RV Chassis | Eugene, OR

Talk to Scott he at Source Engineering he knows these systems inside out.

Like Mike stated my coach which uses the 500ISM Cummins uses intake temp also to control the fan speed and in doing so this may require more time and some data to tell if IAT sensor could be an issue with fan speed rpm.

[bluepill]

Link to S-D electronic controller description.


http://www.flodraulic.com/assets/fdca-11005337-web.pdf


Although it does not apply to Thermowax Valve systems, it gives a good overview of system control.

[jacwjames]

Thanks for the info.

Mike
My manual describes how the system should work and basically the way you described it.

My problem occurred when I had the radiator changed, prior to this I seldom heard the fan running at the higher speed. Most of the time by the time we exited off the highway and pulled in somewhere the engine temps were back down to ~180 so the fan would be back at an idle.

Now I can start my rig and let it idle and as the engine speed creeps up the fan immediately comes on at 180 (based on my Silverleaf). Once it comes on I haven't heard it go off until I shut the engine off and let it cools some.

I'll post my results once I install the new thermo valve, I already have received shipping confirmation and will have it early next week.

[Mike Canter]

It will be interesting to see if the new thermovalve changes anything. Did they change your thermostat when they replaced your radiator? What operating temps did you see with the previous radiator? Did the engine run cooler before?

[RobRoy]

First let me say what you describe is most likely a wax valve issue.

O.K. Im horrible at putting things in my head to the keyboard and make sense on the screen but here I go.

A while back I posted here that I had an issue with my dash a/c and low performance and it only did this when first started and the engine temp was low and before coming up to normal operating range untill the cooling fans came on line.

So I gage checked the a/c and found 400 high side and 90psi low but after the vehicle reached normal operating temperature it worked fine and pressures were good as was outlet temps.

What I found out that that the condenser fan (same set up fan as radiator fans on my coach 500ism) was not running while the engine was warming up to reach normal operating and found out that was the a/c performance problem otherwise everything worked fine.

So I called source engineering and talked to Scott about it and he offered a couple of possible solutions one of which was to install a .018 orifice in the hydraulic lines he said this would make the fans run a med idle speed the sec the engine was started .

So I purchased the .018 orifice it was cheap got it installed it in the hyd line @ 1 min job to do. I started the coach cold and walla! Gage readings normal when engine cold and warming up , outlet temp was chilly willie and I could hear the fans running and they were running and running pretty fast, much faster than I expected for an idle situation and didn’t care for it .
So Mike Canter and I discussed it and I opted to take the .018 orifice back out just not us the HVAC until the engine temp came up to normal and all is well and the .018 orifice is in the tool box for now.

Sooooo that being said and I guess what I’m leading to in this long winded post is that Iwhen they replaced your radiator I wonder if they installed a restrictive orifice in one of you fan hyd lines changing things just enough that you hear the difference?

[jacwjames]

Yes they did change my thermostat, I saw about the same operating temp until I started to climb hills and it would push into the mid 190's. Now it runs ~180 and when climbing hills it will not get above 184-5F.

[jacwjames]

Robroy,
I don't they added an office to my circuit. I sent an email to the Cummins shop manager and he said that the system was not Cummins but installed by Monaco. They didn't have a clue as to the problem.

I checked all the other lines, none had been removed. I believe they just suspended the fan assembly from the chassis after they unbolted it from the radiator. The only 2 hoses they had to remove were the 2 hoses going to the thermo valve.

[Coma]

FWIW my temps run 177-184 under normal circumstances. A hard pull will run them up to 193. Transmission runs about 10F hotter. My fan definitely has more than on on and idle.

[Mike Canter]

Jim, there is idle temps up to 184 degrees +- a few degrees which is one fan speed because the wax in the thermovalve does not start melting until 184*. At 184 the fan speed starts speeding up as the wax melts and by 199* it is at fully melted and the fan is at full speed. That is the design of the thermovalve.

[jacwjames]

Mike,
Yes, I now fully understand how it works. My fan goes to full speed as soon as the thermostat opens at 180F (based on Silverleaf). When I plugged both hydraulic lines to the thermo valve the fan went to full speed. When I put a union in the 2 lines the fan is at an idle. Monaco tech says that this indicates the thermo valve is bad.

I ordered the valve last week and received today. Will try and put it on one day this week and report back.

[Mike Canter]

Sorry, meant that to be for Coma and not you. Too many Jims

[Coma]

Originally Posted by Mike Canter

Sorry, meant that to be for Coma and not you. Too many Jims

Thanks, Mike!

[jacwjames]

Coma
If you have an operators manual for your Dynasty there is a good description of how the cooling fan system is suppose to work. In my manual it towards the end ~page 360.

[Coma]

Originally Posted by jacwjames

Coma
If you have an operators manual for your Dynasty there is a good description of how the cooling fan system is suppose to work. In my manual it towards the end ~page 360.

Thanks, I have the manual for a 2001. I'll check.