BRUISER

Hey all,

I have been trying to get my blower fan to work since I bought this truck with no luck.. and now that the temps are in the teens it is kind cold in the AM

I have replaced the Blower motor
I have replaced the Fan blower switch and still no luck
I also checked the fuses and nothing

I need some help..

If I can not get this to work this week then I am gonna by pass it and put in a toggle switch..

I know the heater works because at 65 I can feel the heat
and the vaccum works cause when you have glove box out of vehicle and start it, you can see the vaccumm things move and the doors open and close from feet to vent.

ANy help would be great

Thanks

here is what the switch looks like


I need to figure out where the 4 wires coming off the back go.

wannadiesel

In the sticky there's a link to some online wiring diagrams. Your heater wiring is the same.

BRUISER

OK I have ripped apart the dash and stil have no power to switch

here are two pics I took

this is back of Fuse box if you look you will see a orange and a green wire those also go to the switch..


this pic shows the wires that go into back of switch


I need to find out where the orange gets its power from before the fuse box..when I check that wire at fuse box it has no power.. any ideas>>??

BC847

Gimme a moment to illustrate this in words . . . ..

BC847

NOTE: Wire Color/Coding

10TN is a 10awg wire that's Tan in color. 16BL is a 16awg that's Blue in color. 12LG is a 12awg wire that's Light Green in color. . . . Get it?

The prefix: C7 or C12 might be Circuit 7 or 12 of a given group. Not sure of that.








That wire of the fan switch you call orange is actually Tan. It is conductor C4 of the A/C And Heater - Diesel Engines schematic. More accurately, C4 10TN.

It is the 12v hot wire that supplies power to the different blower speed positions of that switch.


The Tan wire at the fuse block has nothing to do with the blower. Forget it.


OK


From that plug the wire goes to a splice located behind the radio/AC control section. It's a taped bundle of wires. The splice is to the left of the clip holding the bundle to the large AC duct that feeds the floor vents.

At that splice, you connect to another Tan/10awg (C4 10TN), and a Tan 12awg wire (C4 12TN).


OK


C4 12TN goes to terminal 2 of the Blower Motor Resistor.

C4 10TN goes to the main AC selector control.


OK

As I see it, the power flows as such ~


C4 10TN of the mode selector appears to be energized when the selector is in the Max AC, AC, and Hi/Lo position. From there the power goes to the splice. From there as C4 12TN ,it feeds power to terminal 2 of the resistor. As C4 10TN, it comes to the plug of the speed switch.


I hope this helps more than confuses.







Oh, by the way. Clear your desk, POP-QUIZ!

Source ~ 1993 FSM

BRUISER

Ok I read this three times and I guess the question I am either missing or do not see is where does the C4 10TN get its main power from??

does it come from fuse box, or ignition , or where?

It has to come from somewhere and I do not think it is an always constant on connection??

Thanks

NoSparkplugs

I'm in the same boat as bruiser. Sometimes the bloody thing works, and sometimes not (usually at the most inopportune times). I played with the resistor a bit and I don't know what I did but I had the thing working like it should for a whole road trip. It sure was nice to have heat after a long day of snowmobiling in the alpine!

I'm just about ready to buy a generic switch and bypass it .

BC847

C4 10TN is energized by the HVAC selector switch. Power is applied when the selector is in the Max AC, AC, or the Hi/Lo position. The power that feeds that section of the selector is C1 10BR (10awg Brown)

That brown wire (C1 10BR) goes to a natural color, four pin plug. The other side of that plug has the color code change to a 12awg Dark Green (C1 12DG). It goes to the Fuse.



Let me flow the 12v power from the fuse to the speed switch~

Here goes . . .

From the 30 amp fuse, take the C1 12DG to the four pin, natural color plug assembly. On the other side of that plug, take the C1 10BR to the HVAC selector. There, with the selector in Max AC, AC, or Hi/Low, power is applied to C4 10TN. It goes to the splice with C4 12DG. As C4 10TN, it goes from the splice to the fan speed control.

I think that four pin natural color plug is located right behind the glove box (not real sure about that though).



Anybody speak latin?

BC847

I'm editing this after I post it. Forgive me.

It's a lot to sort through.

BC847

The 30 amp Blower fuse gets its power from the ignition switch.

Let's back-track it (From fuse back to power source be it batt or alttr).

We leave the #1 fuse (30 amp) on a 12awg Black with an Orange Stripe (A22 12BK/OR) and go to sheet 10 . . . . . hold on . . .. (There's 89 sheets of schematics).


A22 12BK/OR appears to connect to the A2 terminal of the ignition switch (Only energized when the ignition switch is in the RUN position). That same ignition switch's pole gets its power from Terminal B3. B3 is fed by A2 12PK/BK which goes to the charging system. . . . .. Geez!

BC847

I've looked at this mess long enough now.

Let's see what's going on.


Get a length of 12awg wire. About 15 feet long.

Connect one end to the positive terminal of the battery. Be careful what you do with the other end. This is your HOT WIRE.


Now . . .

With the fan speed switch on high, and the AC selector on Max AC, and the ignition switch in the run position . . .

Touch the hot wire to the 12awg Pink w/ Black strip wire at the ignition switch (terminal B3)().

If the fan runs, you're not getting 12v power to that ignition switch section. That's another group of schematics. DOH!


If nothing . . .. Turn off ignition switch.



Touch the hot wire to the 12awg Black w/ Orange stripe wire (A22 12BK/OR ) at the A2 terminal of the ignition switch.

If the fan runs, that section of the ignition switch has failed. Must replace ignition switch.

If nothing . . . . . .



Touch the hot wire to the A22 12BK/OR side of the Blower fuse.

If the fan runs, wire A22 12BK/OR from the ignition switch has a break in it somewhere.


If nothing . . . . .

Touch the hot wire to the C1 12DG side of the blower fuse.
If the fan runs, the fuse or it's holder is bad.

If nothing . . . . . .


Touch the hot wire to the C1 10BR at the AC selector switch.
If the fan runs, there's a break in C1 10/BR - - - - 4-pin plug - - - C1 12DG - - - Fuse

If nothing . . . .

Touch the hot wire to C4 10TN where it connects to the AC selector switch.
If the fan runs, that section of the AC selector switch is bad.


If nothing . . . . .

Touch the hot wire to the C4 10TN wire at the fan speed switch.
If the fan runs, there's a break in the wire from the Ac selector . . . . C4 10TN - - - Splice with C4 12TN - - - - - AC selector switch.

If nothing . . .

Touch the hot wire to C7 12DG at the fan speed switch.
If the fan runs, the speed switch is bad.

If nothing. . . .. .


Touch the hot wire to the C7 12DG at the plug at the blower motor.
If the fan runs, there's a break in the line from the speed switch.
(From the motor back to the switch . . . . C7 12DG - - - >change< - - -12BK/TN - -- Same 4-pin plug - - - C7 12DG - - - splice with the same wire - - - one to the Hi speed position of the fan speed switch, the other to terminal 5 of the speed resistor.


If nothing . . . . .


The fan motor's bad or isn't grounded properly.



NOTE, this only addresses things with the blower in the high speed setting which effectively removes the speed resistor from the equation. Further, this iswith the AC selector switch in the Max AC position. This section of this switch may be defective in the AC, or Hi/Lo position.



Barring no power to the ignition switch as discussed above, I'm stumped if this doesn't find the problem.

Hope this helps.

Let us know.

BRUISER

WOW "BC847"

you rock.. that is a lot of helpful info.. I think my problem is in my ignition switch.. i found a few loose wires and one not plugged in :0

but i did cheat for the time being and wired in a toggle switch to positive on blower motor.. so I now have High Fan if I turn on toggle switch ( was nice to have heat this AM )

I hope to go threw all the wiring this weekend and see if I can find out where the power is not getting threw..

PS: you going to Dyno day in Durham??

BC847

Yup. Hope to see you there.

I'm fixing to dive into my blower issues so this was a good primer.

ofelas

I know this is an old post, buy by golly, this helped me out no end this past weekend.
Thanks!

BC847

It took seven years, but I'm glad it helped.