2008 superduty blower

[stew47]

Hello all. Our blower motor only works on 3 and 4. Any ideas?

[Tal_IL]

Common problem. I just replaced mine the other day. Mine would only work on high. Just do a Google search on "2008 Superduty blower motor resistor" and you will find a bunch of info and how-to videos.

They are generally located either behind or below the glove box.

[Gdetrailer]

stew47 wrote:
https://youtu.be/Cr4bLzCOsuE

appears to be behind glove box. seems easy and price seems good...lol so itll be something else.

I seriously don't know what I would do without this forum.

Not under the hood.. Probably not the connector but it does look like it could be a printed circuit type of resistor .. So it could have gone bad (like a break in the circuit board)..

[stew47]

https://youtu.be/Cr4bLzCOsuE

appears to be behind glove box. seems easy and price seems good...lol so itll be something else.

I seriously don't know what I would do without this forum.

[Gdetrailer]

stew47 wrote:

Gdetrailer wrote:

stew47 wrote:
Hello all. Our blower motor only works on 3 and 4. Any ideas?

Common problem when living in the rust belt..

For whatever reason, Ford opted on a lot of trucks to place the resistor pack UNDER THE HOOD near the blower motor..

The problem with the location is the plug/connector to the resistor pack gets a lot moisture.. The result is one or more of the connections on the plug or even the resistor pack end up corroding and eventually fails..

The result is you start losing one or more of the fan speeds with the exception of #4 high fan speed (#4 Fan High bypasses the resistor pack).

Ran into this one on my 2003 F250, lost #2 then #3 speeds..

Pulled the connector to find that the resistor side terminals had rotted completely off..

With some work and several bits of copper wire that I flattened out, I was able to successfully rebuild the resistor pack connections.

If, it ends up not the resistor pack connection then I suspect that your fan control switch may be toast..

Thanks. I'll look under hood and see what I find. I would think if switch goes bad either one speed or all speeds would be down but who knows.

Which is kind of why I pointed you to the resistor pack connector..

BUT, keep in mind, the switching action on the switch is not all that simple, it actually has a complex pattern to it by shorting out one or two of the resistor sections it can come up with 4 speeds..

The way it is wired #1 low is all the resistor sections in series.. and #4 bypasses the resistor.. So it is possible the problem can be the resistor/connection OR the switch it's self..

Matter of conquer and divide in the troubleshooting part..

Although it looks like for 2008 the blower resistor has been redesigned..



FOUND HERE

My 2003 uses an old school open resistor..

like this..



But I suspect that the connector corrosion problem may still be the same if it is still located under the hood.

[stew47]

Gdetrailer wrote:

stew47 wrote:
Hello all. Our blower motor only works on 3 and 4. Any ideas?

Common problem when living in the rust belt..

For whatever reason, Ford opted on a lot of trucks to place the resistor pack UNDER THE HOOD near the blower motor..

The problem with the location is the plug/connector to the resistor pack gets a lot moisture.. The result is one or more of the connections on the plug or even the resistor pack end up corroding and eventually fails..

The result is you start losing one or more of the fan speeds with the exception of #4 high fan speed (#4 Fan High bypasses the resistor pack).

Ran into this one on my 2003 F250, lost #2 then #3 speeds..

Pulled the connector to find that the resistor side terminals had rotted completely off..

With some work and several bits of copper wire that I flattened out, I was able to successfully rebuild the resistor pack connections.

If, it ends up not the resistor pack connection then I suspect that your fan control switch may be toast..

Thanks. I'll look under hood and see what I find. I would think if switch goes bad either one speed or all speeds would be down but who knows.

[Gdetrailer]

stew47 wrote:
Hello all. Our blower motor only works on 3 and 4. Any ideas?

Common problem when living in the rust belt..

For whatever reason, Ford opted on a lot of trucks to place the resistor pack UNDER THE HOOD near the blower motor..

The problem with the location is the plug/connector to the resistor pack gets a lot moisture.. The result is one or more of the connections on the plug or even the resistor pack end up corroding and eventually fails..

The result is you start losing one or more of the fan speeds with the exception of #4 high fan speed (#4 Fan High bypasses the resistor pack).

Ran into this one on my 2003 F250, lost #2 then #3 speeds..

Pulled the connector to find that the resistor side terminals had rotted completely off..

With some work and several bits of copper wire that I flattened out, I was able to successfully rebuild the resistor pack connections.

If, it ends up not the resistor pack connection then I suspect that your fan control switch may be toast..

[mbopp]

Harvard wrote:
Some resistor packs have an in line thermal fuse that go open.

That would kill it entirely. OP says it works on 3 & 4.

[Harvard]

Some resistor packs have an in line thermal fuse that go open.

[mbopp]

Best guess is that the resistor pack is open. All of the ones I've seen are located in the blower plenum. You may have to remove the glove box door for access.