Cat C13 Fan does not shut off.

air conditioner issues will keep the fan on..

 

What model is it. If it has cruise on the steering wheel you can hold the on and the set at the same time to get codes off the odometer. If you do this with the motor off and the key on with the left turn signal on it will reset the system.

 

high pressure switch

 

Hey there I had been having the exact same problem with the fan on my C-15. I don't think the difference in motors should matter. Anyways I lived with it for about six months. What I would do is when the temp is under 175 I would kick the truck into neutral and let the motor idle for about 15 seconds. Then when I put it back in gear the fan would be off. If this works it could get him buy until he can get in the shop because like mine, the fan clutch hub itself is probably wore out and locking into position. You can check the fan clutch hub yourself if you have shop air availible. Just unhook the airline running into the fan and use shop air to see if the fan will pop out and free spin. If it does this then you will know that the problem is either the ecm/solonoid, if it doesn't then it's the fan cluch. I think in your friends case that would be the best way to figure out the problem. Hope this helps ya out!

 

On my c-12,,,the sensor in the thermostat housing went south,,,the pins on that deutch conector where all rotted and corroded,,,replaced the sensor,,,put the new pins and a new plug on,,,and the fan has stayed off!!!
I was getting a check engine light code,,,something about high or low voltage for coolant sensor,,,,try to pull the plug off the sensor,,,if its stuck and won't come off,,,chances are its corroded itself on,,,and its finished!!!! Hope that helps!!

 

It could be something as easy is that the air line came loose of the clutch fan.
That is the first thing I would check. Will also cause a minor air leak, which DOT do not like.

 

check for air leaks, and electrical connections. If it has power at the air switch the switch is probably bad if no power the computer is turning the fan on and you need to take it somewhere they can hook it up and see why. Anything else you do is just a guess. I have found the cat dealer to be most helpful and least likely to dig into my wallet just to hook it up to their computer and tell me whats going on. Good luck

 

If your temp sensor has gone south, the default on CAT's ECM is to activate the fan full time. As I recall when mine went, the temp gauge actually read 190 +/- but never moved. Even on a steep climb up Golconda Summit in NV it just stayed on 190 degrees.

 

had the same problem with the same truck (posted on here about it). Turns out my problem was a bad ecm, kept switching the fan into safe mode, keeping it on all of the time to protect from imaginary overheating