04ctd

saw another thread on only working on high...

but mine works on low mid mid, but not on HIGH.

and it's HOT down heah!

anyone got a quick description of the circuit off top their head?


http://www.dodge.com/bodybuilder/200...nditioning.pdf

edit: looks pretty simple, a cascade resistor, with 3 resistors (one for each reduced speed)

and HIGH being a straight wire.

page 2 of 8.

Bark

This might help. I think somewhere in the thread somebody described it pretty well but finally decided it wasnt the resistor, it was actually some gunk on the wire connector. https://www.dieseltruckresource.com/...l-t271246.html

EDIT: Just noticed it is probably the same thread you already saw. Oh well.

04ctd

nope, good thread, that was what i needed.
this the KEY:

OPERATION
The blower motor switch directs the blower motor
ground path through the mode control switch to the
blower motor resistor, or directly to ground, as
required to achieve the selected blower motor speed.

power comes from the battery through the ignition switch, to the FAN, and then to the resistor pack, and up to the switch.

so...IF you UNPLUG the FAN, you can't track 12vdc thru the resistor.

if you leave the fan plugged in, and check the yellow lead,
the voltage goes down as you change the fan speed, it's kinda funky, so pay attention.


my high power lead has a bare spot, looks like the insulation melted & pulled back.

one other lead has insulation which has burnt black.

i can't figure mine out. i am gonna buy a new resistor pack in the morning, see what's up. will parts stores have those, or just dealers?

here's some pics for other guys to work on thiers:

Bark

Good pictures. Wonder what would have caused that?
Saw this in one of the posts, dont know how true it is but it said:
""be forewarned... the biggest cause of resistor failure is the bearings in the motor are going out....i replaced two resistors before i replaced the motor... the bearings bind up and cause the motor to not rotate as it should, in turn causing the resistor to over heat and burn out"" Wonder if that could cause wire damage.

Does the cover come off the resistor pack? Just wondering if you can see if any of the wires in it are fried. Dont know how much they cost but awhile back I think I saw someone say they were $50 bucks at the dealer but much cheaper on line and the auto parts stores.

04ctd

it was $50 at autozone.

$45 with discount


did not fix it.

with motor off, and in the quite, you can tell High Speed is the same as LOW.

which, to me, seems to say it is grounding out across the whole resistor pack, because the high speed wire is open from the resistor pack up to the switch.

gonna play 'Mr Multimeter' some more today. got school till it gets REALLY hot

tks for the help, this is chapping me

04ctd

well, following the schematic, on HIGH, the switch just provides a straight path to ground.



i checked the continuity of the wire, from the fan plug, to the resistor plug, over to the switch



that wire was good,
and we know the ground is good.

so it has to be an open in the switch.

took the screw out that holds the back of the switch in,
It's already out in this pic,



released the snaps, and pulled it off.



it looks like the back of the switch had melted thru to the copper area,
and was holding the switch away from the high terminal area.



so i cleaned it up with a dremel.





and then i took the rotor off the back of the ****,
and hold the dremel perpendicular, so that i got a nice FLAT new spot on it,

and touched the three contacts.



here's the problem: those kind of gave the switch "the feel" of a click in between settings.



so i lost the feel, but i got the fan back to working.

the switch is $145 at parts stores.

i may just grab a spare next time i see a newer Dodge at the junkyard.

i left the new $45 blower resistor in there. you could SMELL it baking, just smelled like plastic. reckon that was all the manufacturing residue.

i put flex loom over all the wires, not sure if that is cooler on the wires, and better than smashing them all together in electrical tape.

04ctd

(exceeded max 10 images in above post)


the selector on the back of the **** looked burned, like it was giving poor/high resistance connectivity.

i used a bunch of dielectric grease in it, after i washed & cleaned everything up, then re-greased, and re-assembled.



all the pics:
http://s19.photobucket.com/albums/b1...arts-for-sale/

Bark

Dang, you take good pictures!! Noticed 60 others have viewed your post so I am glad they have gotten to see them. Wish I could help but you seem to be in a new area.

04ctd

ha ha..thanks....that's the cheapest camera the Navy Exchange had... $150 on sale for $100, got another ten bucks off because they could not find the box.

i took ~30 pics, and those few were the only ones usable


one the mods can change the title to "how to troubleshoot HVAC fan wiring" and put it into the FAQ or something.

i never intended to get this deep into it, but it's HOT HERE
and at $150 for a new switch, i am very CHEEEP (refer to camera story above....)