1999 kenworth t2000 with detroit 60- fan won't shut off.

I drove a '96 Freightliner with a Detroit. One day the fan came on and stayed on. The cause was a pressure switch on the a/c . The mechanic changed it and it was fixed. I don't know if this will help and this happened in the 90's, so I hope my memory is trustworthy.

 

5 or 6 dif. things can make fan run, If you are paying for all this guess work start buying the hi press sensor lone ranger told you about and unscrew it an change it without lose any freon,

 

I think the fan clutch requires air pressure to release it,,think maybe there is an air leak in the clutch or the sir line going to it

 

I know the ground wire on solenoid has a lot to do with fan.

 

Fan is controlled by engine temp, ac high pressure switch which could go bad freon or no freon in the system, manual fan switch, also intake temp on some older Detroit this goes bad and shows a much higher value than it really is making the fan come on also on t2000 have seen the manual switch act up and keep fan running

 

Without a scanner no way really maybe u can try to just the ac switch with a piece of wire bridge it together and see but not sure try to disconnect manual switch as far as intake temp goes sensor is really cheap so u can just swap it out