Engine Cooling Fan Erratic

[ronandsue74]

During my recent trip to Florida I noticed that my engine cooling fan was not consistent. When it's working properly, the fan will go to high speed at 206F degrees and cut back to low speed at 182F. During this trip the fan would switch to high speed and remain on high keeping the engine temp at 177-179 degrees. Then for no apparent reason it would go back to operating normally. I was not able to determine any consistency to this erratic behavior. The fan might run on high for an hour or two then suddenly start working normally again. Turning the engine off and restarting didn't seem to make any difference. I have hard wired the Sauer Danfoss controller and checked all connections that I thought might be the problem. It is my understanding that my air conditioner has the ability to turn my fan on high when my evapertator needs more cooling. I would like to investigate this but I don't know how. Any advice on how I can check this out would be appreciated. 

The coach is a 2005 Country Coach Inspire 330 with a Cat C-9 Engine. My fan controller is a Sauer-Danfoss 1090385 S/N:1215877. This is the three pin controller that gets its input directly from my ECM. It does not have sensors like some of the Danfoss controllers have. Due to the inconsistency of the problem I'm thinking it's not the solid state controller itself but its getting erratic input or perhaps something else I'm not thinking of. 

Thank you, CCRider

 

 

 

[dickandlois]

On 3/8/2019 at 8:28 AM, ronandsue74 said:

During my recent trip to Florida I noticed that my engine cooling fan was not consistent. When it's working properly, the fan will go to high speed at 206F degrees and cut back to low speed at 182F. During this trip the fan would switch to high speed and remain on high keeping the engine temp at 177-179 degrees. Then for no apparent reason it would go back to operating normally. I was not able to determine any consistency to this erratic behavior. The fan might run on high for an hour or two then suddenly start working normally again. Turning the engine off and restarting didn't seem to make any difference. I have hard wired the Sauer Danfoss controller and checked all connections that I thought might be the problem. It is my understanding that my air conditioner has the ability to turn my fan on high when my evapertator needs more cooling. I would like to investigate this but I don't know how. Any advice on how I can check this out would be appreciated. 

The coach is a 2005 Country Coach Inspire 330 with a Cat C-9 Engine. My fan controller is a Sauer-Danfoss 1090385 S/N:1215877. This is the three pin controller that gets its input directly from my ECM. It does not have sensors like some of the Danfoss controllers have. Due to the inconsistency of the problem I'm thinking it's not the solid state controller itself but its getting erratic input or perhaps something else I'm not thinking of. 

Thank you, CCRider

 

 

 

Thinking the issue might be in the Hydraulic Valving that controls the fan speed. The setup can be quite different depending on model and year.

The issue can be caused by wear of motor vane material - that can contaminate the HY fluid. 

Question: is the cooling hydraulics driven off the transmission or a separate system that needs some TLC, perhaps including new fluid and filter replaced.  

Rich.

[jleamont]

CCrider, has this been an issue from back in 2014 that wasnt resolved?

 

[rayin]

You might change the oil filters inside the reservoir. Just remove enough oil to change the filters, then refill with fresh oil as specified.  The only reason to change all the oil is if it is obviously contaminated per mfgr. of the hyd system.

[wolfe10]

1 hour ago, RayIN said:

You might change the oil filters inside the reservoir. Just remove enough oil to change the filters, then refill with fresh oil as specified.  The only reason to change all the oil is if it is obviously contaminated per mfgr. of the hyd system.

Let me qualify that:

The oil on the outside of the filter is "unfiltered".  Unless you drain all of it before removing the filters, you will mix unfiltered oil with the oil inside that has passed through the filters.  NOT a good idea.

Better to siphon all the oil from the outside of the filters. Remove and replace the filters.  Then, refill with new oil or if the old oil looks really good, pour that in.  It will then be filtered before going through the high pressure pump and hydraulic motors.

[rayin]

1 hour ago, wolfe10 said:

Let me qualify that:

The oil on the outside of the filter is "unfiltered".  Unless you drain all of it before removing the filters, you will mix unfiltered oil with the oil inside that has passed through the filters.  NOT a good idea.

Better to siphon all the oil from the outside of the filters. Remove and replace the filters.  Then, refill with new oil or if the old oil looks really good, pour that in.  It will then be filtered before going through the high pressure pump and hydraulic motors.

Guess I should have included that I use an oil suction gun to remove about 1/2 the oil from the reservoir after removing the top cover.

[ronandsue74]

I appreciate the input. I drained the reservoir and replaced the three Nelson hydraulic fluid filters in December 2017 and filled it with fresh fluid. 

Brett, please give me your opinion regarding the air conditioner fan control actuator. Where is it most likely located and how do I test it.

jleamont, In 2014 when I was having the overheating problem I had the controller reprogramed from variable to on/off and that resolved the problem. This was recommended by Sauer Danfoss. 

 

[wolfe10]

Ron,

Sorry, no first hand information on your coach's dash A/C system.

If (OK, big IF) your A/C condenser is in line with the CAC and engine radiator, you COULD have a switch/relay that turns fan speed to high when the dash A/C is turned on.

Many coaches (including our 2003 Alpine) do not, so A/C performance was not very good unless engine coolant temperature called for higher fan speed.

So, I would ask on one of the CC forums.

[ronandsue74]

ok, thanks Brett