I need some help from you fine folks.
I have used the best wiring diagram I can find (which I believe to be incomplete) Looks to me like I should have 12v going to the blower and the speed varies (hi, med, low) through resistors to ground.
Am I missing a relay here?
I dont think it would keep voltage on the blower unless maybe the selector switch is in ac, vent, defrost, etc, position.
In other words if it is turned off should be no voltage going to blower because a relay (which I can not find) is not picked up.
I have no voltage going to blower now. I put 12v to the blower under the hood at the plug and got the blower to work and change speeds using the fan control in the cab. this is on a 30a fuse which is good so my guess is I am loosing the 12v through a relay, that is bad or not picking up.
Hope this doesnt sound too confusing but does anyone know if there is a relay that brings in the blower motor if so, where is it and what pulls it in?
also a decent diagram would help.
Thanks

 

Standard heater or AC ?

what year truck ?

Please post pertinent info in original post

 

91 with ac

 

I don't have the exact diagram of your truck either, but I believe you are correct about the hot wire going to the fan. What color is this wire? Is it brown with a orange stripe?

I am thinking right now you do not have a relay.

 

yes i am thinking brown w/orange stripe is right.
i tried following the wirthrought he fire wall to the fuse box but its hard to verify unless I start pulling wires. Guess I could use a meter to check continuity through
you think it comes straight off the fuse?

 

Then bonly comonenets I see listed and show is:

1) A/C heater Function sw
2) Blower motor
3) AC compressor clutch
4) Blower Switch
5) Blower Resistor with Thermal Limiter
6) Clutch Cycling pressure switch

Brown/white wire to # 9 Fuse
EEC connector

No Relays listed or shown.

I can scan and post what I have of that will help.

 

The older diagram I was looking at does show it coming straight off the fuse in the fuse box.

 

As soon as I have time I will trace this out.
What do you think are the chances that the wire came off the back off the fuse block.
I show no blown fuses. So if it doesnt go through a relay, the fan would run in low speed at all times, since the fan speed selection does not have an off position.
Thats what doesnt make since to me. It would almost seem like something should enable the fan to run. I am not saying you are wrong but I still dont see something here that make sense to me.

 

I would check the 30 amp fuse that feeds the blower motor. Make sure the terminals where the fuse plugs in are not spread open. You can also make sure you have power on one of the terminals with the fuse out, and the keyswitch in run.

 

Dave you were right!!!
Let me tell you what I found. Someone had wired in a fuse holder to the back of the block with a 30 amp fuse The extra fuse had no power on it. I pull the 30A out of the block and noticed one of the terminals had a little arching. I then pulled the fuse block. The xtra fuse holder was spliced in to the hot wire on the fuse block and fed the wire going out to the blower. A bad connection where the wire was crimped was why the 30A in the fuse holder wasn't hot.
So I now have a multi speed working blower.
Dave thanks to you and Dennis for responed to my post.