hydraulic fan for rear radiators

[encantotom]

hi oh experts,

when we were at the bus shop today, larry w mentioned that the hydraulic fan came on immediately when the engine started and stayed on.

we both thought it should stay off until it gets up to temp.

there is a solenoid on the hydraulic manifold.

when is the fan supposed to turn on and off?

thanks

tom

[Barry Rooker]

On my 2001 coach, #604, the engine cooling fan comes on at 25% immediately upon starting the engine. It runs at 25% because there's a solenoid that diverts 75% of the fluid back to the resevoir. The DDEC will shut off the power to the solenoid when the termperature gets high enough, causing the fan to run at 100%. This is also the fan's default setting as without the solenoid working, 100% of the hydraulic fluid will reach the cooling fan motor.

In recent years my fan didn't seem to speed up soon enough and there were times I was worried about overheating, so I had Newell use one of the extra pairs of wires that terminate in the SS box at the engine, the one with the remote starting switch. Connecting those extra wires to a SPST rocker switch that's convenient for the driver (me) and the other end to the solenoid, I can now run the fan at 100% anytime I want to. Nice.

[Wally Arntzen]

Tom, my fan is air operated and comes on at 90 degrees and goes off at 85 degrees. I also put a switch on the dash so I can run it continueous in hot weather. Mine has been great and always keeps the temps right where they should be.

[encantotom]

i like the idea of an over ride switch on the fan. i have a bunch of wires in that panel in the engine compartment and i assume at least two of them go to the dash fuse kickpanel. so i will put that on my list of things to do.

thanks for the info

tom

[encantotom]

i actually went and checked out how mine works.

it comes on all the time at a low speed until it detects a temp that the ddec says to turn on the fan to high speed.

i tested it by turning the engine on, and disconnecting the solenoid that controls the hydraulic speed control for the fan. when i unplug the solenoid, the fan goes to hurricane speed.

so mine appears to be set up like barry's and not like richards...

tom