Engine Fan Staying On...

2009 Sterling fan runs constantly with A/C on or off? Any suggestions highly appreciated!

 

i have a 1999 international 9900 with a cat engine in it and the fan stays on all of the time.. truck does not have a fan switch in the dash and there is no power coming to the air switch whitch i tested and is good and will turn the fan off..it doesnt matter if the a/c is on or off.. is the fan completely controled by the ecm or am i missing some thing here.. any help would be nice..thanks

 

You need to hook up to the ECM to monitor the inputs that control the engine fan. Something is commanding the fan on. Most often the A/C fan switch as the engine fan is needed for operation when the high side pressure climbs. Once hooked up monitor the fan switch for A/C command. Jumper the switch and look for change of state. Stuck open switches or open wires to switches are common.

 

Fan not staying on but when I use auxiliary fan, turn on then turn off, I hear a clanking noise. any idea what that could be?