Heater and Defrost Motor Switch Wiring

jeepcj, are you saying that your motor only has two wires coming out of it like mine and they are orange and red? Is your motor grounded? Of so, how? I'd appreciated a photo of your setup if you can post one.

 

Thanks Walt and Howard. I just cleaned up the two wires and the one connected to the live wires running from my switch is orange. The one connected to the ground is black. So I guess it's not stock (jeepcj's setup might shed some more light here). Assuming it's wired correctly for this motor as suggested by Howard, am I stuck with a one speed motor? Or can I add a resistor to one of the live wires running from the switch before it connects to the orange wire running from the motor? If so which wire, the red or orange one, and what size resistor? I assume that the addition of a resistor will lessen the current thereby slowing the motor?

I'm still curious as to how the fixed resistance is engineered as described in the TSM. Is it through the switch? through the wire? If it is through the switch, then shouldn't I be able to switch out the switch and get my two speeds (assuming the orange wire running from the motor will carry the maximum current output . . . if it will not, if it is offering the fixed resistance, then there is nothing I can do to the setup that will make a difference to the fan speed . . . like I said in an earlier post, I don't know if my fan is currently running at high or low speed)?

 

Thanks. I may pull the whole thing just to make sure there's no nesting material, etc. in there.

 

the resistance is in the original motor.(it has two separate windings i think). which ever wire you add resistance too would then be low speed(less voltage =less speed)place it on the corresponding terminal on the switch. most likely your motor is running on high now wired like it is.

 

How do I do that? Sorry, I just don't know much about wiring, current, motors and such. I do have a digital multimeter from RadioShack (model #22-802 - http://support.radioshack.com/support_meters/doc62/62278.pdf), but I don't know how to use it.

 

I think I may have found my answer. I searched the internet for blower motors for intermediate cj5's and found two current oem makes, one from Omix Ada and one from Four Season/Trumark. The Omix Ada motor is advertised as a two-speed motor - http://www.omix-ada.com/2-speed-heater-blower-motor-72-77-jeep-cj-models.html. The Four Season/Truemark is advertised as a one-speed motor - http://www.amazon.com/Four-Seasons-Trumark-35504-without/dp/B000C2O9T4 and http://shop.advanceautoparts.com/we...ASw&vehicleIdSearch=16429&isAllVehicle=false# (see specification tab). Both have two wires, one black and one orange. But the 2-speed Omix Ada motor has the wires entering in the top of the motor housing (away from the firewall). The 1-speed Four Season/Trumark motor has the wires entering in the base of the motor housing (toward the firewall) like mine does. I am guessing that I have the aftermarket Four Season/Trumark single speed motor. I tried to find wiring instructions for this motor online as well, but struck out.

Thanks everyone for all your help. One last question: does anyone have any idea if the high speed on the 2-speed Omix Ada motor is faster than the single speed Four Season/Trumark motor?

 

Sounds good. I'll do that this afternoon. Would it make sense to leave the orange and red wires running from the switch connected to the orange wire from the motor and perform the same steps you suggest on both of them, connecting the lead from the meter to the connector that connects to the switch?

 

Just to make sure we're on the same page here, in my proposal above the orange and red wires would not be connected to the switch during the testing and the wire going to the ground would not be grounded during the testing. They would simply remain connected to the two wires coming from the motor via the butt end connectors you saw in the photo.

Or do I need to removed the butt end connectors and just test the two wires coming from the motor?

 

OK. Here's what I found:

1. When I turn on my multimeter and set it to the resistance range w/o the leads touching, it shows the following - .0L m ohms
2. When I touch the two leads together, the meter shows 0.0 ohms
3. When I connect the leads between the red/orange and black/ground wires, the meter shows .7 ohms
4. When I connect the leads between the orange/orange and black/ground wires, the meter shows .7 ohms
5. When I connect the leads between any the three wires (red/orange, orange/orange or black/ground) and the heater case (after sanding it down til it shows a bright clean metal spot where I placed the lead), the meter does not register anything . . . it reverts back to .0L m ohms

Does that help?

 

as far as the high speed difference i would think they both spin about the same speed.the heater will never be a powerhouse with the factory sized motor. there is an upgrade some do with a later model blower and cage. i just run it on high and dress for the weather... hasn't gotten above 20 in over 2 weeks...had -20 Tuesday morning. brrrrr

 

Thanks for the confirmation. This has been a fun exercise. It's good to know how the motor is wired and working. I get decent heat output and can live with the single speed motor for the time being. Now I need to find a top so that the heater can actually warm up the inside of the jeep this winter.

 

Im sorry, I totally forgot to look at mine yesterday morning. My mother informed me she was getting ready to go spend three hundred and something dollars to get her breaks worked on at the dealer. So I told her "NO WAY"! so, I was late for work and I got the parts and put them on for her in about an hour. I will try and look this morning and see if I can get a pic, but sounds like you have it figured. I want to post a pic of mine anyway if I can because yours looks a lot like mine and mine is two speed, so just curious there.

 

A pic would be great. I figure these threads are not only good for the folks posting, but also provide a library for future viewers/posters. So, the more info, the better.

 

Ohms law sez your motor should draw 17 amps at 12VDC. Just saying.

 

The DC resistance is pretty much irrelevant to the motor operation, I would think. The inductance of the armature and field will limit the turn-on surge. Once the motor is running, the coils have an impedance that is higher than the DC resistance, and the power consumed should be proportional to the work being done.

And I would not trust an inexpensive meter for low resistance measurements. They work fine up around a few tens of ohms to a megaohm or so, but once you get to the extremes of the range, you need better (more expensive) equipment.

So I would contend that all your resistance measurement tells you is whether you have continuity in the field and/or armature circuit.

Continuity between the two wires just tells you that they are both connected to the field somehow. A two-speed DC motor typically has two field circuits in series, which either are run as one alone and two together, or one is connected as a buck or boost coil to the main coil (windshield wiper motors are this way). Connected as a bucking coil (current direction opposing) gives you the slow speed, and connected as boost gives fast. But I suspect this motor just has two field windings in series, and one wire powers both windings, and the other wire powers only one winding.