Heater blower wiring help needed

[marky510]

Hey everybody,

Looking for a little help figuring at the wiring for my heater blower circuit.

 

Here's the situation: I actually have a 312 wagon, I'm 90% sure everything is the same from the doors forward. So... when I got the wagon the blower switch was missing in the dash. I did not pull the heater box personally so I'm not sure how the wiring goes back together. My helper didn't understand to label everything as it came apart (language barrier apparently). Attached is a pic of the heater box and wiring if someone could tell me what's wrong with pic. On the dash harness near where the switch goes I have a blue wire (female bullet) 12v hot all the time and black wire (female bullet) ground. The 4pin connector in the pic only has 3 wires pinned in and 1 open. I guess I'm confused on how to power to the heater box/switch circuit. As I'm posting this... do I need to the power in the open pin on the connector?

 

 

If anyone has a pic of their blower switch out of the dash that I could see the connector and wires, that would be awesome.

 

All of the wiring diagrams I have found don't truly show how it should be.

 

Thanks for any help,

 

Mark

[wayno]

I don't understand what you are asking, as everything you said is as it should be, blue wire power, black wire ground is how I would wire it.

You just need a heater switch, plug it in and call it good.

Are you trying to run the fan without a switch?

Now if you are a positive ground car, I am not sure how that plays into it.

 

I just looked at my 521 fan switches, and they are 4 prong instead of 3 prong, but they have the same connector, so that would not work either.

 

You are likely going to have to plug the blue and black wires in, then with a volt meter find the hot wire in the plug, then jump to the other 2 wires from that hot wire until you find what is desired.

If there is no hot wire in the plug, then you will need someone that knows more than I do, as it is a ground situation that works the way wiper motors work, I don't understand them but they do work even though I don't get it.

[DanielC]

That looks a lot like a 521 heater motor wiring.

The 521 fan switch has four positions, off, high, medium, and low.   When the switch is in high position, the blue wire is connected to battery positive, and the black wire is grounded to the heater.   When you pull the switch farther out, part of a resistor is put in series with the fan motor, and it slows down some.  Pull the switch out farther out, and the whole resistor is put in series with the fan motor.

 

On your heater box, there is a small plate by the fan motor, held with two screws. It has the yellow wires, with other color stripes going to it, with the black plastic over wrap.  That is the resistor to slow the motor down   You should be able to remove the resistor, and see how the wires are connected to it.

[marky510]

Sorry guys just re-read what I wrote and very rambling.

 

Wayno - in the pic you can see I only have 1 male bullet (ground) available to plug into the dash harness. Yet I have 2 female bullets on the harness (power and ground). What do I plug into the female bullet (power) from the options in the pic? If I disconnect the blue section and plug that to power, runs motor constant bypassing the switch and resistor pack.

 

Second question - not really important, but curious. Can you run your blower motor with key off, is it hot all the time?

 

DanielC - How many wires are going into your resistor pack? 3 or 4?

[wayno]

OK, I don't know anything about the 312 wiring or the 312 for that matter.

 

I looked at every 320 heater box I have, none of them have resisters.

 

I went out and looked at my 63(actually 62 but sold in 63) as it don't have as much shit in the way so I could see the heater switch, it is a very complicated switch with a bunch of resistors on it, so the 320 heater box/motor only has a hot and ground wire going to it, yours is like the 521 heater box/motor that Daniel mentioned.

 

All my 521 heater boxes have a small pigtail(4 wire stand alone wiring harness) that goes from the plug you have on the heater box harness(3 wires) to the heater switch, the 4th blue wire coming out of the heater switch in that short pigtail harness goes to a keyed hot source.

[marky510]

Alrighty ... Thanks so much checking all of that. I'll check thru my myriad of boxes that my helper filled up with 312 pieces, hopefully there is a pigtail harness that I need.

Thanks again and I'll keep you posted of the results.

 

Mark

[DanielC]

Looking back again at your heater box, it looks like an early 521 or a 520 heaterbox.   It might be possible that a 521 heaterbox will fit in a 320, but I am not sure.  That is better answered by Wayno.

 

I had a 320 pickup once, a long time ago.  I think it might have been positive ground, but I am not sure.   A 521 is negative ground.  If the 320 is positive ground, the 521 heater motor may run backwards.   But having said that, there were two different heater fan motors used on 521 trucks.  The early type of motor looks like yours.  If it is a type of electric motor that does NOT use a permanent magnet, and uses a field coil, reversing the polarity on the motor, reverses the field magnetic field, and the armature magnetic field at the same, so the motor turns the same way, regardless of the polarity of the hook up to battery power.  If the motor case is grounded, that could cause a short circuit if hooked up wrong.

 

Do you have a voltmeter?  A test light?

[wayno]

If I had a photo of the pigtail I would post it, but I don't, I don't even have an extra one which amazes me, as I don't throw anything away.

My 520 pigtail consists of 3 yellow wires which are Y/L, Y/B, Y/R, and an L wire(keyed 12V), "L" is blue, it is about a foot long.

 

So far all I have ever seen is gray 320 heater boxes, and the 520/521 had black heater boxes, but that doesn't mean they didn't come in other colors.

 

I have seen at least 3 different motors on the 520/521 Daniel, and the rubber piece that connects to the of the heater box is very different in how it connects, shape, and the height of the heater box is different also, not sure if the 320 and 520/521 are compatible, don't know anything about the 312.

[Charlie69]

Here is a link to a 320 wiring diagram on the David Murphy 620 sight

 

http://www.davidcmurphy.com/olddat/data/dat-320.pdf