Hydraulic Fan problems

[Darrel]

My 2007 KSDP has the side mounted radiator cooled with a hydraulic fan motor. I believe that the fan is running at the highest speed at all times. This has a deleterious effect on my MPG (6MPG avg) and is embarrassing to travel through a campground with gravel roads.
My manuals are no help with troubleshooting. The fan motor has a label "CASSAPA" made in Italy. The CASSAPA web site indicates that the fan speed is controlled via a unit (somewhere) that senses three temperature locations (somewhere) and defaults to high speed in case of any failure. The solonoid/controller at the motor is 12volt and 27 watts and is connected via a two wire lead coming from the large wiring harness. I have not found any troubleshooting information and my local dealer only knows that the hydraulic oil is OK. Does anyone on the forum know anything that could help me run down my problem?

Have a nice day - Darrel

[Route 66]

I don't believe there's much you can do yourself other than disconnecting the 2 wires at the fan motor. If the fan is not running at high speed, it will go to high speed with the wires disconnected.

The fan is controlled by the ECU and a Cummins/Spartan tech will need to connect their computer to see what is causing the problem.

On my rig, activating the Jake brake on high will force the fan to high speed as will the air conditioner under certain conditions.

The fan on my rig wasn't even connected electrically when new and I also found I was getting 6 MPG from the fan running at high speed all of the time. It puts quite a load on the engine.

[Darrel]

Folowup: I have taken my RV to a Cummins dealer where they searched for trouble codes from the ECU module. No problems. The tech spent about an hour running various tests and concluded that the fan is running constantly on high speed. ($98 and thanks for your business) They were not able to handle parts procurement.
On my own I have measured the resistance of the bypass electric valve that is supposed to control fan speed. Result: open circuit to the solenoid. This unit is Casappa P/N 280253. No luck with parts from the Casappa company web site. I'll have to contact Newmar for parts and my nearest dealer is over 100 miles away.

["007"]

This outfit has fan controls but different part #'s than you posted. Maybe its a Spartan part #.

[Darrel]

More Diagnosis: Since I had nothing to lose I went after the modulating valve with my screwdriver. On this model the wires attach to the valve via a connector block held on place with a single screw. This connector was not making a proper connection! A little scraping with the sharp end of a safety pin and continuity has been restored.
Am leaving this weekend to a campground that is approached via a mile of dusty road. If I can see anything through the dust behind me I'll know that it made a difference.

thanks for the replies - Darrel