garcia26233 Posted December 28, 2012 Share Posted December 28, 2012 I have a 1999 Mack Ch613 and my fan clutch won't stop. Fan clutch it's self is fairly new but I'm pretty sure that's not the problem. I suspect it's something electrical. Some times driving down the road I hear it come on and off about 3-4times per Second, like if has a faulty relay or sensor. Any ideas or clues?? Where can I find its relay or what sends the signal for it to come on and off. It's air operated, turns off when air is introduced and shuts off when it doesn't. Most of the time 85% it's on meaning it has no air in line to fan. Quote Link to comment https://www.bigmacktrucks.com/topic/29064-fan-clutch-stays-on-relay-sensor/ Share on other sites More sharing options...
Keffer inc Posted January 10, 2013 Share Posted January 10, 2013 (edited) "coolant temp sending unit" bad reading? blown or partially unplugged fuse (#10?) On my 1996 CH, there is a factory jump wire in the harness for an optional on/off switch, could be coming unplugged? (behind the headlight switch panel) Just a couple ideas. all guesses though.... Edited January 10, 2013 by Keffer inc Quote Link to comment https://www.bigmacktrucks.com/topic/29064-fan-clutch-stays-on-relay-sensor/#findComment-156268 Share on other sites More sharing options...
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