M1009 Heater Blower Motor

[JSF01]

This is a bit of a dumb question, that I am 99.9% sure I know the answer to, but I just want to confirm. The heater Blower is not working in my truck, an I am trying to diagnose were the problem is, so I just want to confirm the theory of operations of it. In theory I believe that electricity should be flowing through the motor housing by being negatively grounded through the mounting points, through the motor and out of the lead into the Blower motor resister. From there electricity should flow to the switch than the fuse box before going out to the positive terminal of the battery. So in theory if I take the wire from the terminal on the heater blower motor that leads to the resister, and use a volt meter between the wire and the negative terminal on the battery I should get no voltage when the switch is in the off position, and increasingly higher voltage readings the higher the fan switch is set to. And if that happens the problem should lay with either the motor being bad, or it's grounding being bad, correct? I just want to make sure I am not missing anything like possibly it's not suppose to be negatively grounded through the attachment to the firewall but a separate wire or something.

 

[cucvrus]

Hey I will try to help you out. Your question is in depth. My answer is simple. Just attach 12 volts + to the power spade terminal on the motor and ground the blower motor housing. It will work or not work. I think you have the rest of the issue covered. I hope that helps.

 

[dependable]

Also un plug the radio suppression capacitor on blower motor and plug wire directly into blower spade connector. This is often the problem.

 

[Rvitko]

At least in my case, it was the switch, if i aggressively moved it up and down, I got some life from it. The switch is fairly flimsy when you get it out and you can clearly see if contacts are burned.

 

[cucvrus]

The switch is fine it is the poor connection that is burning the switch. Get a new or used plug for the end and clean up the contacts. Add a little dielectric grease and you will be golden.

 

[Rvitko]

I replaced the switch and it worked since, when I get to my ac install I plan to strip the dash and clean all contacts, thanks for the tip! What you say makes sense, in my case there was heavy arcing in the switch at some point and it was in rough shape, but I can see how a bad plug would cause that. Mine actually looked like it saw some desert duty, I have cleaned at least a quart of fine sand from the doors and under dash and that is without stripping the dash, just dusting off what I could see underneath. At the time I was focused on getting the charging system straight

 

[cucvrus]

Mine sees desert duty everyday. That is the fine dust that you get driving it on dirt roads , gravel roads and off road. It is all sand when it gets in the truck and drys out and rattled around for a few years. Besides all the military bases I was ever on were sandy dusty pits. The further south you go the worse it gets.

 

[JSF01]

Also un plug the radio suppression capacitor on blower motor and plug wire directly into blower spade connector. This is often the problem.

Radio Suppression Capacitor? Would you happen to have a picture of that because I don't think mine has one, or I am just failing to recognize it.

 

[Warthog]

Radio Suppression Capacitor? Would you happen to have a picture of that because I don't think mine has one, or I am just failing to recognize it.

Item #2 in the diagram

 

[JSF01]

Thanks, well mine does not have a radio suppression unit, so that can not be the issue. This has me really stumped I connected a wire from the heater motor positive terminal to the positive terminal on the battery and the heater motor spun which should indicate it is good. I also tested from a good ground the wire that leads from the motor to the resister, and when the switch was off I got no voltage, and low to high got a progressively bigger voltage reading Which If I have my understanding of the system correct, should mean that the resister switch and fuse are all also all functioning properly. When connected together though it's not working.

 

[scottladdy]

Thanks, well mine does not have a radio suppression unit, so that can not be the issue. This has me really stumped I connected a wire from the heater motor positive terminal to the positive terminal on the battery and the heater motor spun which should indicate it is good. I also tested from a good ground the wire that leads from the motor to the resister, and when the switch was off I got no voltage, and low to high got a progressively bigger voltage reading Which If I have my understanding of the system correct, should mean that the resister switch and fuse are all also all functioning properly. When connected together though it's not working.

You've performed some good detective work. I always recommend starting simple. Do the connecters make solid contact with their mating terminals? Are they clean? etc.

Good luck and keep us posted on your progress.

 

[JSF01]

I just realized something looking at the wiring schematics, if I am reading it correctly the way its wired in the CUCV, if you disconnected the plug from the resister the blower should still turn on if you set it to high. If some one does not mind I would really appreciate if some one could confirm that for me.

 

[JSF01]

Well I finally figured out the problem. I turned out to be the positive wire off of the switch connector were it was plugged into the wiring harness. The wire end was corroded and the male connector was a bit loose. What I suspect was happening was while I was unplugging and testing the individual components, I'd cause the wire to make contact well enough that it would give me a good reading. When I would put it back together, it would naturally want to rest in a position where it would not make a good enough it of contact, so the blower motor would not run. I was thrown for a loop when after messing with the resister connector for some reason it the motor blower decided to work a bit. So I wired up a new temporary makeshift connector that would get the system working so it would be able to pass inspection as I wait for the ordered new one to come in. Of course than I wasted a bunch of time trying to figure out why I could not get it to work again, because that connector was not actually the issue and it had been a fluke that it temporary started working after messing with it. Oh well, the system now works as it should so I will be able to get it inspected tomorrow.