detroit 60 series cooling fan not working automatically

If you're talking about the engine fan, you might want to check your thermostats. Usually those fans are thermostatically controlled and if your thermostats are bad, it could cause your fan to not work properly.

 

Might check a pressure switch in ac system on firewall driver side. I think this switch is on hi side of ac system and tied to engine fan auto switch Good luck . Zircon

 

let the truck idle so the engine gets warm. and see if fan comes on while it's sitting. might have to raise the idle as it'll take a long time on low idle. of go climb a hill if you got one close enough that'll heat the truck up.

what is the normal running temp of the truck as your driving down the road? like mentioned above you could have cold thermostats.

if your checking for fan on with a/c. that's not going to happen till your high pressure gets high enough. then it'll cycle on and off. if that don't happen, then it's probably the high pressure fan a/c switch.