Blower motor stopped working

Check resister.
When my heater fan went bad. I had no power levels for a couple days than no power.

 

Is the fuse good? I know on the older 90's Kenworth's the fan switch can melt causing issues.

 

05 had some changes with HVAC system and dash. Post last six and I will get a diagram.

 

Check the relay for the A/C clutch on defrost. I’ve had 2 ‘05 W900L’s have that relay go bad an melt the plug off the back of the fan motor switch.

 

No, not sure what that is. The relay i spoke of is in your breaker panel. Took a while for me to find it because it is in the opposite corner of the panel from the rest of the heat/ a/c related stuff so i never found it when i looked for hot ones. It’s the one that engages the A/C clutch when you turn Defrost on. That module you show i have no idea about, but it’s a safe bet that an electrical device with a wire off it will lead to one or more things not working.

 

Attached the diagram. The blower motor gets power from fuse H11 and is constant with key on. The blower motor is switched on the ground side. The resistor block allows for the low and medium speeds. Hi speed does not use resistor block. Need to check operation of switch. Plugs are known to melt. The broken part you pictured is the freeze protection switch and would be shown in diagram directly above the blower motor. It opens circuit if evaporator gets around 28 degrees to prevent freeze up and only effects A/C compressor operation. I have replaced quite a few blower motors that didn't work in truck, but would bench test "okay". Motors get a bad spot on shaft @ brushes. If you spin it and it takes off again in chassis you have a bad motor. Need any other help let us know.