Engine fan running

[Rockycoon75]

I have a 11 Pete with a 871. The engine fan is running constantly. Hooked up insite and it shows it's in ac mode. Threw my gauges on there and I only have 45 psi on the low side. The AC is working fine when I turn it on.
If I shut the truck off and turn the key back on the fan releases and free spins. As soon as I start it back up it goes back to locked in. Doesn't matter if the A.C. is off or on. I even tried pulling the A.C. relay. I thought maybe a switch at first but don't understand why it would only be bad with truck running.

[5022]

I had my fan hub go bad it was turning itself off and on when I stopped to look it over I turned the key on like you and the play was normal. I called a shop 50 miles ahead to have it checked drove maybe five miles and could smell it burning itself up hit a ramp shut down turned key on and the hub was gone fan had a huge wobble in it.

[Rawze]

(12-27-2017 )Rockycoon75 Wrote:  I have a 11 Pete with a 871. The engine fan is running constantly. Hooked up insite and it shows it's in ac mode. Threw my gauges on there and I only have 45 psi on the low side. The AC is working fine when I turn it on.
If I shut the truck off and turn the key back on the fan releases and free spins. As soon as I start it back up it goes back to locked in. Doesn't matter if the A.C. is off or on. I even tried pulling the A.C. relay. I thought maybe a switch at first but don't understand why it would only be bad with truck running.

some history? when did it start doing this? have you re-filled the system with refrigerant? have you replaced the high pressure switch? have you checked for corroded wiring on the high pressure switch?

Have you disconnected all batteries for 30 min to reset the cab control?

[Rockycoon75]

It has been doing it for a week. I replaced high, low, and fan control switches in July. System was recharged then and hasn't been touched since. I don't see any corrosion on the plugs but I will recheck. I unhooked it for 20 mins (I was thinking that was the time frame) I will try it for 30. I may have some contact cleaner. I will check.

[Moose]

Any recent programming changes? Fan control is a multiplexed operation. Cummins ECM has final say and voltage to the solenoid. Paccar CECU will request and ECM will comply. You really need to look through INSITE and see what's requesting from where and work backwards from there.

[jimeneztrans84]

http://rawze.com/forums/showthread.php?tid=1989

Try this sensor. Happened to me this sensor fixed it

[Rockycoon75]

I will try that. No recent programming. On insite for Fan Control it shows Air Conditioning. Thanks for the help

[Moose]

I'll second the high press switch. That should be the only one that would command it on. I don't remember if you can just jump it or unplug it. I'm pretty sure it's the latter.

I can remember jumping the low press ones on the KW's to get them going until we got everything in to draw it all down and fix it.

[Rockycoon75]

It appears to be the switch. The local Pete store is out of it and KW only has a knock off brand (what is currently on it only lasted 5 months ) You have to jump it to bypass it. Takes a min or so before it kicks out. Thanks for the help. Hope everyone has a good 2018