-
Fan Clutch Hub
Since this subject has got a lot of attention on the chassis thread, I asked Bill Jensen for some feadback.
Tom,
The fan clutches that we use are made to cycle within a pattern determined by Prevost and Linnig, the maker of the fan clutches. As we have moved along from emission controls via the engine software to the use of additional parts to remove the particular matter (DPF) and the NOx (SCR device) we have seen a corresponding rise in the general temperature that we see on the dash gauge for the coolant.
Right along with these devices has come the need to run the engine at a much higher temperature to make sure that the process is done completely. So the fan clutch will run in first speed (about half of engine rpm) most of the time once the engine has warmed up. It will cycle into high speed (engine rpm)as necessary to handle the heat load. The warmer the day and the more that the engine is placed under high loads (climbing hills, pulling large trailers, etc.) the more time the fan will be in high. So the life cycle will be shorter for the newer units as they work to be able to meet the present EPA requirements.
The addition of the large OTR (over The Road) air conditioning systems only impacts the cycling of the fan clutch as an extra horsepower load. The speed of the fan clutch is still controlled by the temperature of the engine coolant. For the small a/c system we have set the system to put the fan into speed 1 as soon as the a/c clutch is engaged if it is not there already. From there on we let the temperature of the engine coolant determine the fan speed except that the fan will go no lower than speed 1 as long as the dash a/c compressor is engaged.
We continue to work to keep the engine in the correct operating range and I am sure that we will see more and different methods to control the fan for the engine coolant.
I hope that this explains this question a bit but feel free to contact me it not.
Thanks!!!!!
-
1 Reply
-
That tracks with what I have been seeing…if my dash a/c is on and the compressor is running, my fan is on full time. When the compressor kicks out, the fan stops if engine temp is low enough. Sounds like it is working as intended. I agree that the newer engines will make it work even harder and will probably shorten the life of the clutch, but what can you do? Higher running temps are here to stay I think…
Log in to reply.