Fan runs continuously

This topic contains 7 replies and was last updated by dominic 12 years 4 months ago
September 20th, 2009 4:19am
I am working on a 2002 Internations 9400i with a series 60 Detroit. We've been working on this truck for years on and off to figure out why the engine fan runs continuously. Solenoid test good, fan clutch releases with shop air, wiring from the ECM to the solenoid has been replaced. When I give the solenoid ground it activates but doesn't when the ground is coming from the ECM. Any suggestions?????
September 20th, 2009 1:21pm
So it seems that you know that the mechanics of the fan system works fine,it is the trigger mechanism is not.Do you have access to a Pro-link or some other diagnostic equipment?A breakout box could come in handy too.You need to find where things are going wrong,is the ECM getting input from the engine to tell it if the engine temperature is too high or is the ECM just not signaling the clutch to work.If I were you I would disable my fan and run the engine to the signal temperature and see if the ECM receives the correct information,note that what dash gauge and what goes in to the ECM may not be the same information,this is where the Pro-link comes in,you can see what the ECM sees.Also do you know the repair history of that truck?Did it have a fan clutch installed in the past?If it did was it the correct one for the truck,some fan clutches are air apply and spring release while others are air release and spring apply.If the wrong clutch is on the truck when it gets to the right temperature it will disengauge and stop working but if the fan is constantly running it may never reach the correct temperature to stop because the engine coolant temperature is not hot enough,thus a constant running fan.Just some of my thoughts on a Sunday morning,hope they might be of help.
September 20th, 2009 1:27pm
Hello Buddy... I'm just guessing, the engine fan run continuously even the engine temperature is low? I will suspect a shorted temp. sending unit that is mounted in the engine thermostat housing. By the way, what is the consequence of fan running continuously? cabin heater not hot enough? I will suspect engine thermostat stuck open.
September 30th, 2009 3:30am
How about the A/C system? I have found faulty high pressure switches in the ac circuit which causes the fan to run continously.
October 23rd, 2009 9:19pm
A faulty air temp reading can cause this.

Thinking the air temp is too hot, the fan will kick in which will think it needs to cool the air going through the intercooler.

My 2 cents
October 31st, 2009 7:37pm
To follow up with Michal...I've had fans staying on with a faulty air temp sensor. It's located in the charge air cooler piping. :)
November 3rd, 2009 10:49pm
High five ;)
November 5th, 2009 3:29am
Yeh just try to bypass em and if it shuts off, or unplug it if it shuts off easy try

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