Automotive Blower Motor & Controller Help

[TX OMFS]

I have a 2008 Ford F350 Super Duty. The blower motor refused to work 3 times in the last 10 days or so, including today after work. I stopped at O'Reilly and bought an aftermarket blower motor and aftermarket "resistor". My vehicle has the automatic temp control option so it's not really a resistor, it's a fancier controller.

After cursing the engineer that designed the subsystem for about 30 mintues I was able to get the old resistor out. I put in the new resistor and left the old motor. The old motor would spin full speed but would not slow down to a lower setting. An improvement but not correct. I installed the new blower motor. Same story, it spins at full speed and cannot be slowed down with the dash controller.

So, what do you think? Did I fry the new "resistor" but trying it with the old fan? Or is the aftermarket resistor just a piece of junk? Is it something else? Everything I read says if it will only run a full speed then your resistor is dead.

I already ordered a new OEM (Motorcraft 9l3z-19e624-b) resistor from Rock Auto.

I struggled to avoid jokes about your mom while writing this OP.

 

[TxStetson]

Having the automatic climate control places the computer into the circuitry which means your aftermarket speed resistor probably won't be effective. When you ordered the OEM resistor board, was there a different option for auto or manual?

 

[TX OMFS]

Having the automatic climate control places the computer into the circuitry which means your aftermarket speed resistor probably won't be effective. When you ordered the OEM resistor board, was there a different option for auto or manual?

Yes, there was an option and I got the automatic.

The aftermarket was suppose to work w/ the automatic system. I would guess you're right and the aftermarket just won't work in this system.

The auto vs manual controllers, OEM or aftermarket, look very different.

 

[kbaxter60]

Your description begs a couple of questions:
* Was the "old blower" not running at all before the first swap?
* You said it's a "fancier controller", not really a resistor. Do we know what this means?
* Related to the last question, do you EXPECT it to respond to the dash controller? In other words, if the cabin is not frosty, not sure you would expect the blower to slow down?
I doubt that your "old blower" broke the "resistor", but would tend to have little confidence in aftermarket parts.
Not sure I have a real answer for you, but might offer some suggestions given answers to the above...

 

[TX OMFS]

Your description begs a couple of questions:
* Was the "old blower" not running at all before the first swap?
* You said it's a "fancier controller", not really a resistor. Do we know what this means?
* Related to the last question, do you EXPECT it to respond to the dash controller? In other words, if the cabin is not frosty, not sure you would expect the blower to slow down?
I doubt that your "old blower" broke the "resistor", but would tend to have little confidence in aftermarket parts.
Not sure I have a real answer for you, but might offer some suggestions given answers to the above...

No, the old blower was not running at all before I swapped the resistor.

The controller is a field effect transistor from what I can tell. It's not a pure resistor like they used to use.

Yes, the truck gives the option of choosing a temp and letting a computer adjust fan speed to hold that temp or allowing the operator to choose both temp & fan speed.

 

[kbaxter60]

No, the old blower was not running at all before I swapped the resistor.

The controller is a field effect transistor from what I can tell. It's not a pure resistor like they used to use.

Yes, the truck gives the option of choosing a temp and letting a computer adjust fan speed to hold that temp or allowing the operator to choose both temp & fan speed.

Helpful. So when you looked at the resistor output with your oscilloscope, how did that signal appear?
Mostly kidding...that is for extra credit.
Based on all reported thus far, it sounds like the blower is okay and the failure was the old "resistor". I think ordering the exact OEM replacement was a good move.
Looking forward to updates.

 

[lightflyer1]

Just went through this with my wife's Hyundai Santa Fe. Replaced both the "resister" and fan. Auto climate control. After market part works fine for ours. My only gripe is the shop charged $350 for the "resistor" when new OEM one was available and only $110 retail. Should have done it myself but too busy with other money making chores. Running well now.

 

[Fishkiller]

I have a 2008 Ford F350 Super Duty. The blower motor refused to work 3 times in the last 10 days or so, including today after work. I stopped at O'Reilly and bought an aftermarket blower motor and aftermarket "resistor". My vehicle has the automatic temp control option so it's not really a resistor, it's a fancier controller.

After cursing the engineer that designed the subsystem for about 30 mintues I was able to get the old resistor out. I put in the new resistor and left the old motor. The old motor would spin full speed but would not slow down to a lower setting. An improvement but not correct. I installed the new blower motor. Same story, it spins at full speed and cannot be slowed down with the dash controller.

So, what do you think? Did I fry the new "resistor" but trying it with the old fan? Or is the aftermarket resistor just a piece of junk? Is it something else? Everything I read says if it will only run a full speed then your resistor is dead.

I already ordered a new OEM (Motorcraft 9l3z-19e624-b) resistor from Rock Auto.

I struggled to avoid jokes about your mom while writing this OP.

Mechanic that I am here is what I do:
- Check Tire Pressure
- Check washer fluid
- Turn all switches on and off
- Take to garage

Hope this helps

 

[Brains]

No, the old blower was not running at all before I swapped the resistor.

The controller is a field effect transistor from what I can tell. It's not a pure resistor like they used to use.

Yes, the truck gives the option of choosing a temp and letting a computer adjust fan speed to hold that temp or allowing the operator to choose both temp & fan speed.

I preface this by saying I don't know the Ford directly. But.. There is most likely no resistor.

The fan speed in most modern applications is controlled via PWM - pulse width modulation. A MOSFET is rapidly switched on and off, and the fan motor speed changes based on how much of each cycle is on vs off. If the fan runs when switched at or near full speed, but doesn't run at any of the low speeds, you may not have the correct type of fan motor for the application.

 

[lightflyer1]

I used to do a lot of this kind of work myself. Much harder now days to get up and down from the ground and working upside down and in contorted positions. Half day jobs now take the weekend.

 

[Ozzman]

No, I don't think you damaged it by using the old blower motor either.
It could be that the "new" resistor you purchased is also defective.

I recently did my AC also on my 2006 Mazda 3 last month because I had similar issues.
Since it came as a full kit (resistor and motor), I replaced the motor first and then swapped out the resistor.
Took me 6 hours to do it too... Like you, I agree that the designers don't care about the maintenance of vehicles, but I digress.

I think you are on the right track. Purchase a new resistor, and if that doesn't fix the problem it could be the harness itself is damaged.
You may have to check each pin for corrosion or if it is damaged.

Good luck.

 

[Brains]

Looks like Ford used two modules for that vehicles, and they both share the same connector and install in the same cavity.

The non-automatic (no numerical temp control) uses a resistor card. Part #3F2Z18591AA
The automatic system uses an electronic module. Part #5F9Z19E624AA

 

[TX OMFS]

Looks like Ford used two modules for that vehicles, and they both share the same connector and install in the same cavity.

The non-automatic (no numerical temp control) uses a resistor card. Part #3F2Z18591AA
The automatic system uses an electronic module. Part #5F9Z19E624AA

Thanks for the info. Where did you find that part number for the automatic system? I came up with Motorcraft 9L3Z-19E624-B.

It's a 2008 F-350 Super Duty..

Thanks!

 

[Texasgordo]

Since it's a 2008 Ford Superduty, you'll probably have to take the cab off the frame

 

[Brains]

Thanks for the info. Where did you find that part number for the automatic system? I came up with Motorcraft 9L3Z-19E624-B.

It's a 2008 F-350 Super Duty..

Thanks!

RockAuto.com and confirmed by a few other sites

There were a few different part numbers listed, probably updated parts as years went by.
5F9Z19E624AA, 7C3Z19E624A, 7C3Z19E624B, 7C3Z19E624C, 9L3Z19E624B

 

[TX OMFS]

Update: the OEM "resistor" 9L3Z-19E624-B came in yesterday. Just installed. Everything works like a charm.