Fan works on 3 of 4 settings ... why?

[Jessie James]

My heater fan was only working on low and high, so I replaced the resistor pack and now I have low, med-low, and high, but not med-high. What's the issue here? Is it the switch in the dash, or something else?

 

[Jessie James]

Anyone?

 

[Fordum]

Well, there are basically only three things in the system.
The switch, the resistor pack, and the fan motor.
Plus, of course, the wiring.

Fan motor does not count, it runs at whatever speed its told. So, either you have a bad switch, broken wire, or the resistor pack you put in is bad.

You might compare the old pack with the new. It seems to me that there are systems out there with only three speeds.
If your new pack looks different, that may be your problem.

Also, make sure that a contact did not push out of the connector when you plugged in the new pack, or one might be burnt.

 

[Jessie James]

Thank you for the suggestion, I'll check the connector. The resistor packs were identical.

I hope it's not a bad switch, I hate taking that dash apart ... in the winter ...

 

[454Sub]

Certain trucks only came with 3 speed fans and some came with 4 speed fans I believe.

I would bet the dash switch, as thats why mine only works on 2 speeds.