ac fan-fuse 27 pass comp keeps burning out

[david ranger]

Hi there,

The fuse burnt out after which i changed out the resistor plus the pig tail connector
mounted under the hood in the fan housing.
They looked pretty corroded.


However , afterwards the fuse went out again.
Any pointers on this?
How could i track down a short circuit here?

 

[Curious Hound]

Do you have a multimeter? If so, you could disconnect the fan motor and
Measure its resistance. That could tell you if the windings are shorted. But the problem could be that the fan is stuck or almost stuck. If it won’t turn freely, it will pull too much current and blow the fuse. Also, make sure you are using the proper size fuse. How old is the truck?

 

[RonD]

Just FYI

The speed control in the dash is the GROUND for the blower fan
The resistor block is for the GROUND going to the blower

In 2005 fuse 27, 10amp, in the cab fuse box is NOT for the blower fan
Fuse 13, 30amp, in the engine fuse box is for the blower fan

Fuse 27 powers the dash selector/mode switch and blend door, and does activate blower relay in engine fuse box, which connects fuse 13 to blower motor
You could try pulling out the Blower Motor relay in the engine bay fuse box, and see if fuse still blows
If so then either the Blend door motor is shorted or there is a short in the dash selector switch

Diagram here, 2005 and 2006 are the same

 

[david ranger]

First, thanks for the fast and elaborated reply.
As I am situated in Dutch Caribbean, probably the car from new (2005), only used the AC or one would drive with open windows.
The temp switch probably has never been used as you do NOT want hot air.
We have enough of that ;-)

Please note that the fan worked for a whole week and then blew.

@eric: thanks, i will try that

@RonD: i now see from your drawing that this car has an actuator to blend cool/hot water.
My experience is limited to manually powered valves by cables.
We learn every day.

I do not understand the difference between the blower and the blower fan.

So can i conclude that i could pull the relay and the blower fan would still work?
As i am not interested in the actuator working, could i circumvent something?

 

[RonD]

Blower and blower fan are the same

No, if you unplug the blower relay the blower will no longer work, but if fuse 27 no longer "blows" then that relay may be bad

If you fold down the glove box all the way, you will be able to see the blend door actuator, and you should be able to unplug its connector and then see if fuse 27 no longer "blows"
Video here on how to remove actuator but you just want to unplug yours to see if its causing the short

If neither the relay nor the actuator removals help, and fuse 27 still blows then you have a shorted wire, you will need an OHM meter to find which wire is shorted to ground
You will need to pull out the selector and vent control panel to test wires

If you remove the passenger side kick panel you can see the whole fuse box, its actually called the SJB
Drawing here: https://ww2-secure.justanswer.com/uploads/s420/2010-04-02_183353_05_Ranger_DLC_fuse_location.jpg

Connector 2280b is where fuse 27 wire goes out, and these SJBs are known for bad connections, so you may want to pull off that connector and have a look for any corrosion on the pins or slots

 

[david ranger]

Thanks RonD. I will test these things.

 

[david ranger]

I unplugged the connector from the actuator and no fuse blown since.
Thanks Ron D.

 

[david ranger]

I jinxed it bij posting this Friday. Yesterday the fuse went again. When replacing it, i saw dust and rubbish below under in the fuse box so i will clean there and check out that 2280b.

 

[david ranger]

I removed all dust with vaccuum blower and paintbrush and after that cleaned everything with electrical spray.
That 2280b connector. How to remove that? There is a handle on top.
Do i need to slide that down before removing?
It seems a bit stuck and I do not want to break things.

 

[RonD]

The "handle" will pull out the connector as you pull up on it, like a lever, it pushes down on the boards housing lift connector out
"handle" should go back down as you push the connector back into position

 

[david ranger]

Thanks. Had to use some force. Was a greenish corrosion of one the pins in the leeft below corner.
Cleaned it with ciopper brush and electrical spray.
Let us see if it holds out.
The handle also needed some persuasion to go back in its original position.

 

[david ranger]

Fuse still blew out. So i will measure which wire shorts to ground.
Anyone has the diagrams for me to know which wire runs where?

 

[david ranger]

Do you have a multimeter? If so, you could disconnect the fan motor and
Measure its resistance. That could tell you if the windings are shorted. But the problem could be that the fan is stuck or almost stuck. If it won’t turn freely, it will pull too much current and blow the fuse. Also, make sure you are using the proper size fuse. How old is the truck?

Thanks Eric B.

I skipped this step so will do that first.
The truck is from 2005 and AC fan is used every day.

What resistance should i measure ? 0?

 

[Curious Hound]

I just measured this one from '93 and got 2.8 ohms. I would think a newer one might still be in the neighborhood of 3 ohms

 

[RonD]

+1 ^^^

Over 2.5 under 6

0 = shorted