2007 vision cxn613 E7 Fan won't shut off

[Shahid]

Hi,

Have a problem with when I start the truck in morning, the fan keeps going full speed and truck does not warm up even if I idle for half hour. Once I drive for about 5 km's the fan disengage's. This is an issue because in canadian winter it becomes a Popsicles before it starts to warm up. It is electric BEHR clutch on this. if i disconnected the wire the to the fan clutch still runs same on start up. Is there a way to shut it off manually or does it have a problem I should look at 

Thanks for your help.

[Mackpro]

This is normal operation 

[Mackpro]

https://pdf4pro.com/amp/cdn/service-bulletin-mckenzie-tank-lines-685fa.pdf  This explains operation and troubleshooting of fan clutch. The colder the weather the longer it takes to disengage after cold start . 

[Shahid]

Thanks for your help. Can I put an override dash switch for this?

[Mackpro]

There is as no option for fan override on the  electric viscous fan  for the Aset engines that I ever saw. The option was available for the air fan though. I have seen guys use a dash switch wired in line with the green high pressure AC switch up by the radiator. Cutting the power to the AC switch makes the engine ECM think there is high AC pressure and turns the fan on . 

[Joey Mack]

I may be off the mark here,  but..... cant you just set the 'smart fan' setting to the opposite setting it is on and see how it does..  it's called 'smart fan' but.... really?? jojo

[Mackpro]

The override might actually work after all , I just read the bulletin I attached and it said there is a over ride switch for the electric viscous fan, . There are two different harness connections for the 2 types of ECM controlled fan clutches. There are 3 settings for the fan clutches on the ASET’s.  “Smart Fan “ which is the electric viscous, “ On/Off” is the air fan  setting, then there is the “None” which is a regular viscous fan. If you select the “On/Off “ setting then only the 2 wire connection at the rear of the engine harness will work, it would connect to the fan clutch solinoid for a air fan . If you choose the Smart Fan setting then only the connection at the electric viscous fan clutch will work. Also choosing the On/Off setting you are able to set engagement and disengagement temps and run times . The fan clutch is controlled by the engine Ecm but the override settings are controlled by the vechicle ECM ( VECU). 

Edited November 27, 2021 by Mackpro
Correction