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C9 COOLING ISSUES

Yahoo Message Number: 29170
We have an '05 37' Allure 470 with the Cat C9. The cooling system is a mystery to me and all who have worked on it.
When on the steep back country passes in CO last summer both the analog and Silver Leaf reported too high temps. At the top of the pass we would stop to cool off, and no luck because the fan was at low speeds. A vist to theCat dealer in Salt Lake was somewhat productive after they checked the Silver Leaf against their laptop on several runs up the local interstate pass. They finally changed the temp sensor at the top front of the engine and it stopped the overheat, but not the erratic cycling of the fan speed. I don't have to add cooling fluid now. They wouldn't do the fan speed analysis CC requested, apparently because of difficulities getting reimbursement from coach mfgs.
Buddy Gregg Knoxville didn't have any luck resolving the fan speed issue and also didn't do the requested fan speed analysis. Their opinion is that my situation is normal, which I doubt.
So, the current story is that after a minor warm up while picking up campground lines the fan will spend the next four hours on the highway going through wild cycles of low to high speed in sync with the Silver Leaf which is reporting temps up to 229 which the fan reduces to 165. Some days the analog gage never gets into the normal range.
I have had many interesting talks with CC without results. Seems they install several temp sensors on the engine during buildup and we have a game of who owns the problem.
Any ideas or reports of success on this issue would really be appreciated.
Chuck Rudning

Re: C9 COOLING ISSUES

Reply #2 –
Yahoo Message Number: 29177
Chuck,

I had a very similar experience with my Cummins ISC powered Allure.
Sometimes the engine temperature would behave quite normally, then rapidly increase and decrease sporadicly. Other times the fan would run at full speed even from start-up with a cold engine, and then shut down after the engine finally warmed up. The temperature sensors checked out OK. I found the problem myself by removing the Danfoss fan controller and testing it on a home-made test bench mockup. The problem was a faulty connection inside the fan control module. The module is not repairable. Being a retired EE with some time on my hands, I constructed a micro-controller based unit of my own design. It has 1600 miles on it and has maintained coolant temperature much better. As a bonus fuel economy improved from 7.5 - 8mpg to 9.1mpg. It still needs some tweaking, but is a big improvement for me. NO more dust storm!!
If your CAT uses a Danfoss fan control module, I would have that checked out or just replaced. These fan issues can be very frustrating, as the service techs don't seem to understand them very well. This is a rather simple system and should not be so difficult to troubleshoot and repair. Just search the messages here for 'dust storm' and 'fan controller' and you will get an idea of what many have gone through to get it resolved.
Good Luck!
Dave

2000 Allure 36'
#30444

c.rudning@... wrote:

Re: C9 COOLING ISSUES

Reply #3 –
Yahoo Message Number: 29184
Hi Chuck,

I would like to add to the responses.
There are 3 posibilities.

The fan is controlled by the C9 ECM, The fan is controlled by a Danfoss with OEM sensors added by CCI, The fan is controlled by another controller with OEM sensors added by CCI. In any case, getting a procedure to test for proper operation for your configuration is the first step.
Fred Kovol

Re: C9 COOLING ISSUES

Reply #4 –
Yahoo Message Number: 29185
Hi Chuck,

I would like to add to the responses.
There are 3 posibilities.

The fan is controlled by the C9 ECM, The fan is controlled by a Danfoss with OEM sensors added by CCI, The fan is controlled by another controller with OEM sensors added by CCI. In any case, getting a procedure to test for proper operation for your configuration is the first step.
Fred Kovol