'81 F100. I'm confused about the control wiring circuit. According to the '81 diagram, the Heater is on a CB, but mine is a 30A fuse. The wiring diagram shows an Orng wire going to a blower-switch terminal. It also shows a Brwn/White wire coming from the blower motor. Those 2 wires are noted going to the Fuse. I've always thought the blower control-switch was switching the Ground through the resistor pack. The resistor has a 3-wire connector for the Low/Med/High fan speeds from the blower switch and a 4th terminal which is direct-Ground. What is confusing me is the different color power wires that show to be coming from the same 30A fuse...1 to the blower-switch, the other coming from the fan-motor.
The '80 and earlier models have a circuit diagram that make sense, but the '81 doesn't, to me anyway.
Can someone clear this up for me? Thank you.

 

Send a pm to Franklin he is the best when it comes to wiring and circuits.

 

I did that. Thanks. I'd post the diagram I'm using, but don't see a way to attach it in a post.....

 

Load it into your gallery and then post it. I don't have my diagrams with me right now.

 

Diagram I'm using. I tried delineating the circuit with highlighter pen, but it didn't transfer very good. Circuit is at top of diagram.

 

Well, I don't know about sizing in bytes. I'll try to get it better

 

I can't read that diagram. Maybe it will help if you can tell us what is wrong with your blower.

 

I need to make a new wiring harness from the blower-switch to the resistor pak. That diagram is wrong so it's just as well it can't be read. I copied it from the Autozone site, where I made my mistake. It shows an Orange wire coming from the fuse to the blower switch.....that is wrong and what was confusing me. It should read as an Org/Blk wire going to the resistor pak and then controlling the blower speeds through the resistor pak grounding function. The motor power circuit goes to one terminal on the motor/through the AC function switch and to the fuse. That is what I always thought the control was, until I saw that AZ diagram...........mea culpa, y'all

 

That Diagram is indeed wrong.

This one isn't however. 1981 Heater wiring Diagram.



Black/Orange wire (Circut #181) comes off the fuse panel (F-14) 30 amp. Goes to the motor directly, (non-a/c) or to the a/c mode switch (A/C).

(A/C only) Brown/White wire (Circut #182) goes from a/c mode switch to blower motor positive side, but changes color at connector #606, to Brown/Orange wire (circut #181) before reaching the motor.

(A/C only) Brown/white wire (Circut #182) also splits and splices off at splice #603, and powers the a/c mode switch, for the A/C evaporative thermostat, the a/c clutch solenoid, and the carb solenoid (If Equipped) BEFORE the A/C mode switch.

(A/C only) Light Green/Purple hash wire. From the a/c mode switch, for switched power to the A/C evaporative thermostat, the a/c clutch solenoid, and the carb solenoid (If Equipped) AFTER the A/C mode switch.

The ground for the blower motor Orange/Black wire (Circut #261), is the one hooked between the blower switch and the blower motor resistor, and as you say. With the switch on high, this wire bypasses the resistor for High Speed.

Red/Orange hash, (Circut #260) is Low speed, (or medium low on a/c).
Light Blue/Orange hash (Circut #269) is medium, (or medium High on A/C)

The A/C blower resistor differes from the non-a/c and has four wires, and is permanetly grounded with a Black wire (Circut #57) for low speed, when the a/c mode switch is activated.

Hope this helps.

 

Yes, it does! Thank you very much. I appreciate your help

 

Yes this is wes and I don't know alot bout wiring.. on my 1981 ford f100 , after getting my truck back from shop they had to do bunch of work to it but after running the AC to make sure it was cold enough..The compressor was making the belt flap like it was loose but it was properly tight, too much current was being sent to fuze box and it melted the fuze into the fuze box.. I don't have any wiring diagrams and I have been searching on Google and no luck.. if anyone has a diagram can u email it too me at.. welowright@gmail.com. Also does anyone know what would cause that to happen? I haven't had any problems with it before.. thanks yaw and have a blessed day

 

1981 EVTM diagrams are available on the Gary's Garagemahal website.

There is no such thing as "too much electricity being sent to the fuse"
You have too much power being drawn by whatever is downstream of the fuse.
There is a short somewhere.

 

Hey this is wes .. thank you ArdWrknTrk I'll look at that.. does anyone have a 1981 ford f100 4.9 ltr with factory heat and ac , that can show me a picture of the blower motor where the wires connected to the prongs and the heater core box with the wires connected to the prongs please .. mine has upper prongs and lower prongs but the upper prong looks like one prong is cut flush .. does this all song proper for this model truck with factory AC and heat?? .. But it has only a single wire connector to it. I'll show pictures of mine later tonight..Thanks yaw

 

Here is a link to the 1981 troubleshooting manual. 1981 EVTM - ???Gary's Garagemahal

You might find you will get a better response from the forum if you start your own thread with all the specific details of your own truck and issue instead of replying to an eight year old thread.

Pictures are always good.
The harness between motor and resistor block is different with a non-AC truck.
I usually find that the plug has melted or the resistor fuse has overheated, but I'm not quite sure what you are describing.

 

AC compressor has only one black wire going to the heater core box from what I can gather from the color of the wires.. is this the only wire that the compressor is suppose to have for this 81 ford f100 4.9 ltr with factory AC ?
Another picture of compressor showing the wire coming from behind the clutch..
Showing connectors on the heater core box.. you can see the top prong on the left looks like it has been cut flush... Is this the way the factory did it or is it supposed to have another wire connected to it ? Can't remember if it was like this when I first bought it.
Shows the same connectors on heater core box with wire colors.. top wire is solid black ... I assume it is the wire coming from the compressor , can't tell for sure because they all are wrap up ... Am I right on this? Also bottom three wires are( from left to right)..orange with black stripe and then a blueish or greenish wire and then the red wire...Is it connected properly or should this bottom connector be connected with, (from left to right) red wire the greenish wire and then the orange with black stripe wire?
Wires connected to the blower motor...Left wire is solid orange wire connected to brownish/ orange wire.... And right wires are black wire connected to solid orange wire.. Is this black wire coming from the compressor? Also can you tell me if these are connected right? Thanks and thank you ArdWrknTrk .