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Hydraulic Fan Question

Yahoo Message Number: 78583
My fan operates from the time the engine starts until the engine is shut down. Is this normal?

Gil B

'05 Inspire
51322
C9 Cat

Re: Hydraulic Fan Question

Reply #1 –
Yahoo Message Number: 78587
Gil,

My understanding of the later Country Coaches is the fan will turn any time the engine is running. It should be turning slowly when the engine is cold. When starting cold does the fan make a lot of noise or is it fairly silent?
If it's really making a lot of noise you could have a problem with your fan controller.
The reason it turns all the time is there were problems causing damage to the mounting hardware with the fan starting from a full stop. Lots of instant torque. So with it turning slowly all the time the problem went away.

Barney

07 Inspire 52059

Re: Hydraulic Fan Question

Reply #2 –
Yahoo Message Number: 78592
Not sure how the newer coaches perform, but my 2000 Allure fan always runs with engine running. The fan has different fan speeds that are dependent on the temp sensors for coolant and air. Also, setting OTR AC to MAX will cause fan to go to highest speed. If the fan runs on high speed all the time, then there is a problem with the control circuit. Could be a temp sensor(s), AC, or fan controller. There is much discussion already on board about the fan.

Jim Hughes

2000 Allure #30511

Re: Hydraulic Fan Question

Reply #3 –
Yahoo Message Number: 78596
My fan runs at full speed for several seconds when the bus is started cold. It then calms down to a slow idling speed. As the engine coolant warms up, the fan cycles between full speed and idle to keep the coolant between 198F and 204F. Those are the temperatures reported by the silver leaf. My understanding is a sudden fan start from a dead stand still creates damaging forces to fan, pump, spline and hydraulic hoses. Starting the fan from an idle speed helps reduce these forces and resultant damages. At about 32K miles, my system seems fine. Here's a look at my pump spline connection: http://muniac.smugmug.com/Maintenance/PTO/i-fMCGzh5/0/M/img1996-M.jpg That's the story on my bus. You may experience a different phenomenon.
I gather that those with a constant run fan won't experience excessive starting forces. The initial start of the fan when the engine starts would be, by definition, a soft start. My guess is some engineer decided to conserve energy by cycling the fan on and off. A simple and cheap reprogramming of the software in the engine controller was all that was involved. This, of course, didn't address the complete solution. One problem gets fixed and one or more problems get created. Those with busted fan mounts, eaten up splines and trashed hydraulic hoses already know the down sides of partial engineering.
Also the wire connected to this sensor: http://muniac.smugmug.com/Maintenance/Misc/i-RGGmJFc/0/M/img1293-M.jpg is somewhat loose (on my bus). Air blowing over the wire and other mechanical movements has caused an intermittent connection (just my guess). On one occasion it had spooked something that had caused the fan to stop running altogether. Engine temperature quickly zooms out of control. I had this happen on one trip but luckily I spotted it on the silver leaf and was able to pull the bus over and shut it down before I boiled over. Unplugging the 3 prong connector to the fan controller valve will cause the fan to run constantly. I did this, restarted the bus and finished the trip without problems. Since then I've not had a repeat of this situation. At this point I'm still not exactly sure just what went on. Got to love those intermittent problems.

At 05:54 AM 4/16/2012, you wrote:

Re: Hydraulic Fan Question

Reply #5 –
Yahoo Message Number: 78606
Jim - Bus information is all the way at the bottom. IE - Last lines in the thread.

At 06:26 PM 4/16/2012, you wrote:

Re: Hydraulic Fan Question

Reply #6 –
Yahoo Message Number: 78622
I do not know about this cycling question, but I will pass something along to everyone: I was recently at Colton having some work done that involved pulling the cooling package. They discovered that the bracket that holds the fan was cracked all the way through in one of its four arms. They said this is very common. You would probably never notice this until you pulled the radiator.

Rich 2002 Magna.
 

Re: Hydraulic Fan Question

Reply #7 –
Yahoo Message Number: 78674
Rich,

Thanks for the info. I will have to check my mounts next time I am under the coach.

Jim Hughes

2000 Allure #30511