rvndonbon Report post Posted September 18, 2015 What is the easiest way to determine if the hydraulic fan controller is working properly? When I start my motorhome when engine is not hot radiator fan seems to run fast. After engine warms fan slows down. Could this indicate a problem with the controller? Share this post Link to post Share on other sites
wolfe10 Report post Posted September 18, 2015 rvndonbon, Please tell us what year, make and model coach you have. Does it have a wax-type or electric-type fan speed control? Share this post Link to post Share on other sites
rvndonbon Report post Posted September 22, 2015 I have a 2001 National RV Tradewinds LTC with a side radiator with a Sauer Danfoss Hydraulic fan system. Share this post Link to post Share on other sites
wolfe10 Report post Posted September 22, 2015 This might be something to consider: http://sourcerv.com/conversion Share this post Link to post Share on other sites
rvndonbon Report post Posted September 22, 2015 Thank you Brett, I have read about this system in the past but am trying to make sure it's my controller before I spend the money to replace it. My fan seems to run quite fast when I start the engine and it's cold but slows down when the engine is at normal operating temperature. I know the fan defaults to high speed if controller is not working at all but what will it do if the controller is defective or is that not possible? Share this post Link to post Share on other sites
wolfe10 Report post Posted September 22, 2015 Do you have any symptoms of fan controller failure? It should work as follows: Low speed (not off, as you need some air flow over the CAC even with low coolant temperature) until a few degrees above thermostatically controlled temperature. Said another way, if the thermostat is 190 degrees F, you only want the fan to kick to high if the coolant temperature is, say, 195-205. It should then switch to high and drop coolant temperature back to 190. If it does that, all is good. You would need much more chassis-specific information (from Freightliner, I assume) to be able to say what speed fan should run at what engine RPM/coolant temperature. But, unless the fan roars all the time or does not kick to high as described above, not sure I would be too concerned about it. But, as a Preventive Maintenance item, be sure to change the hydraulic filter(s) per Maintenance Schedule. Two basic types-- oil filter-type screw on and large fluid reservoir with stacked filters inside. Again Freightliner can tell you exactly what your chassis has. Share this post Link to post Share on other sites
