96 peterbilt 379 fan problems

On my Horton fan clutch it can be bolted to be locked in full time. They are designed to stay on if the system fails, no air... full time fan... at least on my 6NZ

The only time I've ever had a fan not come on was when the fan walked off the hub shaft some.

Good luck.

 

Bean man youve got mail.

 

This is one thing I really hate about Petes. If the fan loses air or power, it won't come on, bad for engine safety!!! Behind the tach panel there should be row of fuses, one of them is for the fan. I know the circuit also goes through a relay. Problem is if the fuse is blown there is a short somewhere!

 

my 2000 379 has the same problem, I had to toggle a new hot wire to the actuator to run manually, any more ideas?

 

I'm needing help to.

ok. Before I bought this truck 4 years ago some idiot has went and ran all kinds extra wires to the extra switches ,
Now I have a cut off engine switch on one of my switches , if the switch is in down position it will try to start but won't start. It has to be up to start. So I have a train horn and the push button switch went bad so I opened up panel where all the extra switches are and I noticed some wires went to nothing they were hooked up to switches but was cut at other end. So I took the wires off. Now there were 2 wires just stuck down in one of the switches for the engine fan to manually turn it on. So I took them out put an end on them and stuck them back where they were. Now that I did that all of a sudden I manually turn my fan on and my truck dies.
I didn't not move any wires. This wiring is so messed up. Now what I need is how can I run a separate switch myself with out even messing with the ones already in my truck to be able to manually turn my engine fan on and off if I want to. It cuts on automatically on its own. But as when it gets hot outside it gets up to 200 Degrees before it cuts on and only way to keep my truck ac cool at that degrees is turn on and run engine fan while I sit and idle truck at 1000 rpm .
Where would the wire be going to the fan so I can do that on a separate switch I install myself. And just leave the other switch alone. Cause aparentaly it has to stay in down position to keep the truck running now all of a sudden.
So what I'm asking is I need to install a manual fan switch and need to know where to find the wire to do it from the engine fan.
Cat 6 NZ 475 single turbo.

 

You need to find the schematics for the wiring and fine which wires are for the solenoid for the fan. The wires should be coded.
Second, Cat recommends when idling, to kick up the rpms enough to keep the oil pressure running at 60 psi. I personally keep the fan manually on when idling with the A/C on. It saves the fan clutch.

 

Yes. I always idle till it
Oil reaches At least 60. And that's why I need to figure out why all of a sudden I turn of fan it turns off truck. Cause I always ran fan when I idle and sit.
Thanks for help

 

I’m having similar issues. I have a 1987 pete 379. Fan works fine when I flip the manual fan switch and works somewhat fine when the engine gets to 200 degrees. My main problem is the fan won’t kick on with the AC compressor running. It will let the AC system over pressurize. I changed binary switch, changed the expansion valve. Flushed the system and put new r134. Don’t know where else to look. It seems behave like an electrical issue. Couple days it would stop working in certain instances but now it won’t work at all. What am I missing? Could it be the fan solenoid? I doubt it because it works ok I guess...