Fan clutch turning on too early

[Mack Gazza]

l have a 2004 Mack Qantum with a 470ccrs motor, have fitted a new fan clutch as the old one would not keep air, worked fine for a while but now it still turns off at the correct temperature but turns on way too early thus running with fan turning on and off too often.

l would like to  find which sensor or thermo switch sends the signal to the ECU for turning on the fan clutch. 

Thanks to all of you readers,

Mack Gazza 

[mechohaulic]

can't help with that ;2004 is brand new to this ole  man, LOL . you should receive an answer soon when these "youngsters" wake up . LOL now a  R/U or similar system= is different. 

[Joey Mack]

the coolant sensors are at the rear of the rearward water manifold. one is in the side and the other points toward the firewall.  The A/C pressure switch also controls the fan.  there may also be a setting in the EECU for ''Smart fan''.  I cant remember if the air fan has that feature turned on.  I also dont know how Aus. trucks are built, compared to U.S trucks..  jojo

[Mack Gazza]

Thanks Joey Mack for the sensor location, replaced the reward sensor which at least told me the old one was working then replaced A/C low pressure switch as you suggested ( the small one closer to the compressor) and whammo it is operating correctly which l am very happy about. 😊 

Thanks for this awesome forum.

Mack Gazza.