Engine fan for 1998 379 pete

The temp sensor tells the ECM when the temp gets over 205 degree to turn the fan on then if you are running the AC it has a high pressure fan switch on the AC line to send a pressure signal to the ECM and it will turn the fan on also. If it has another manual switch in the dash to turn on the fan manually that is a totall of three switches it can have to turn of the engine fan. Is the fan staying on all the time or something or not comming on at all.

 

It's basically controlled by water temp.,unless you're running your A/C, then it cycles off and on with your A/C. If it's not coming on, check the small airline going to the fan clutch. If it's cracked or off the clutch won't engage. ( even if you have a manual switch ) I had a Detroit in mine, but I think they're all air operated. good-luck.

 

On most fan clutches if it is cracked or the line off the fan will stay engaged it takes air to disengage it. Now if your fan hub is leaking internally than even with the line hooked up and air going to it it won't disengage the clutch to turn the fan off. If this is the case the fan hub needs to be rebuild or replaced with a new one.

 

You might be right, but I think on my Detroit it took air to lock it , I don't remember, sold that truck a couple years back. What you said actually makes more sense.

 

Well Im basing my data off the 3406 E cat like she they usually have a horton hub on them. but you are right there was some fan clutches and models of them that took air to engage them so that is right. It just depends on what kind of fan hub, year model of truck and what kind of engine you know all that kind of BS. We acually had a 1982 W-900 KW that had that kind of fan hub design your talking about but i don't know no how many companys design them that way anymore.

 

Does it say there on the fuse box lid what exactly that #3 fuse is for. Is it just the engine fan fuse. If thats the case it sound like your manuall switch in the truck is stuck internally on to a closed circuit. It may just need a new switch put in it. If the fan cycles on and off with the AC then the clutch fan is working and isn't bad I would check that manuall switch on the dash.