Why does my Peterbilt not engage the fan?

Why does my Peterbilt not engage the fan?

The air solenoid will engage the fan when unplugged and it seems that when I turn the manual override switch to “on” I’m still getting anywhere from two to five volts out of the #11 pin at the ecm wire that supplies or takes away voltage to the fan solenoid. The diagrams I’ve recieved fromn our local peterbilt dealer are illegible to say the least.

Where is the AC switch on a Peterbilt?

The reason I ask is because the AC switch and the manual fan switch can be wired in series on the wire from pin 11. Or they can be wired directly to the engine ECM and report independent of the wire 11. If you have a service tool you can go into configuration screen and see the programming.

How to run Peterbilt a / C in a truck?

While your adding watch and make sure your engine fan still cycles. Then turn fan speed for blower motor to 2 and make sure the compressor will cycle off at some point. The system cycles off of pressure because there is no freeze switch. So the system is very sensitive to proper charge.

Why does my engine fan keep coming on when the a / C is off?

You could have a bad high press switch on the A/C. Thats the swtich that will turn the fan on when the A/C is on and say your not moving to get air flow. Unplug the swtich and put a jumper wire on it and if the fan stops you found your porblem. They can go bad and make the fan stay on even with the A/C off.

Do you know if it takes power to engage the fan?

As I am sure you may know, the engine ECM sends out 12 volts on pin 11 when the ECM wants the fan off. When it wants it on, it removes the power. Many times this wire 11 is routed through the manual fan switch and sometimes the AC switch. Sometimes it’s not. Do you know if it takes power to engage the fan? Or no power will engage the fan?

What does it mean when your radiator fan is not working?

This is what we call a blown fuse. A blown fuse is no big deal, and changing one does not cost a lot of money. If your car’s radiator fan is non-functional, check your car’s user manual and locate the fuse for the radiator fan controller or the fan.