Bunk blower not blowing

A simple switch just connects 2 wires together when you turn it on -- if it has just 2 wires try jumping them together if you can !

 

If you are relating to the heater then it you won't notice anything at first. The unit has to heat up before it turns the fan on. It's like a 2-5 minute delay. Turn it on and wait.

If it is something else let us know.

On some there's an override switch up front on the dash.

We need a little more detail what's not working. A picture of the panel would help.

 

use test light to ck. for power in one of wires at turn fan switch.

 

Yeh try what CondoCruiser or baha says, he would know better - i have to assume that wiring in the trucks have become more complicated than what i said --but then again if it is a simple toggle switch maybe not.
I have to assume that those units (I have 0 experience with them) may have a thermal breaker also.
I do have a mechanical background --but 0 experience with the diesel truck mechanics --or bunk heaters.

 

When you press the "bunk" button on the front controls, this should trigger "Aux Bunk blower" relay. If not, the button on the main control may have failed. Just because the light comes on, doesn't mean the signal is going out. If the auxiliary bunk relay is working, this is sending power to the fan speed control knob in the bunk control panel. This power is sent through wire #75AS, green in colour. After that, the different speeds go through different circuits with different power sources. It is extremely unlikely to have all fan speed circuits fail at the same time to cause the fan to not work at all. If the control is getting power, chances are the blower motor itself is no good. The rust you found is probably the root cause though. Also, there is no time delay. When you turn the controls, the fan will be on.