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Discussion Starter #1
I have an 84 that I just replaced the blower motor on a a week ago. It worked fine for a couple of days then last weekend I couldn't get the switch to turn it on. The fuse is fine, the new motor is fine. I tore apart the dash to try to take out the air control unit and when I was moving it around in the dash I had the key on and the blower kicked on. I checked the diaphram also and notices that it wasn't moving when I was sliding the bottom knob. I really need a quick fix to get me through the workweek and until I get paid. Any ideas?
 

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Zombie Hunter
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I think in the 84's the selection door is still vacuum controlled, if it's not working you have a vacuum leak or disconnect somewhere so the air dam isn't working.

If you "moved it around" and it started working, you have an open somewhere in you're wiring, and when you moved it, it closed, check all connections for the blower.
 

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Discussion Starter #3
I got the selector vacuum leak taken care of but the blower switch is still intermittent. I couldn't find any loose wires but I tracked it down to the plug in the back of the switch. Anyone have any ideas? I wouldn't mind bypassing the fan speed switch and having it run full if it would solve the problem for now.
 

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Zombie Hunter
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I got the selector vacuum leak taken care of but the blower switch is still intermittent. I couldn't find any loose wires but I tracked it down to the plug in the back of the switch. Anyone have any ideas? I wouldn't mind bypassing the fan speed switch and having it run full if it would solve the problem for now.
if it's in the plug, run to a boneyard and pluck one off another bronco and splice it in.

when you pulled the plugs you might of bent up the contacts in the plug, make sure they are all connecting. If your moving the plug up and down and making contact, that may be a problem.
 

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Discussion Starter #5
Ok. I got a harness repair kit to replace the plug into the blower motor switch because it was melted. Hooked it up and I'm 100% that its wired properly. This morning I couldn't get my horn, radio, cruise control to work and the blower still will not come on. I checked all fuses and they are good. The fuse panel is not melted or shorted at all. Any ideas? I'm not worried about anyhting except the heater right now since I have to drive to work with the windows open and it's a 45 minute drive for me in 30degree weather. I really am stuck on this issue now that it has spread.

If it helps the blakc/orange wire on the plug was the one that melted it and I'm almost sure that's the one from the fuse panel to the switch. It matches up but I couldn't see it the entire way.

Please help
 

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FSB Pimpster & Recruiter
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Rob, I think he is having some kinda short between his Blower motor switch, which may of caused him to blow the fuse for the Cig. lighter when he was moving things around in the dash...

MGustafson, Do as Rob mentioned go to the bone yard and pick up a GOOD harness... Most of them burn out in the HIGH section. It could also of ruined your switch... GOOD LUCK & Welcome to Our HOME! :thumbup

Allcruisen :imp :usa
 

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Discussion Starter #10
I'll start checking grounds since I'm off tomorrow, but I know the harness is good. I started my truck today when leaving work and the blower magically worked. I played with the switch and found it won't do anything but high so I know the resistor is burnt. Even after that though the rest of the stuff that wasn't functioning still won't work. I checked the fuses again just to be sure and they are all good. I even switch them out for new ones just to be positive.

If I can't figure this out in the next day or so I'm going to have to put it in the shop and hope they can figure it out.

Rob:
When you say "burned an open" you just mean that one might have shorted and come loose right?
 

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Look under there for some bare wires that could cause it to ground out as well. Tuff to tell with out having it right in front of you
 

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Zombie Hunter
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Rob:
When you say "burned an open" you just mean that one might have shorted and come loose right?

If you start running a lot of current due to a short through some smaller wires, you may actually burn the wire to the point where it no longer functions as it should, the resistance is too high. It may actually get so hot it breaks inside the insulation. Black is the common color for ground in our trucks. Burnt black wire insulation sometimes sneaks past you.

If you burned that plug up that way, i would assume that the ground that it runs to should be checked, just with all the current running through it might have ruined the wire, and the black wire is covering it up.
 

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Zombie Hunter
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Look under there for some bare wires that could cause it to ground out as well. Tuff to tell with out having it right in front of you
i'll second that. electrical problems (AC and DC) are the hardest to trouble shoot without being physically able to touch it.

i know what i am thinking and how i would check it, but describing it to someone becomes a pain.
 

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Zombie Hunter
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and keep in mind that a short is a little different than an open:thumbup
yea be careful with the terminology.

A short will read differently on a digital multimeter than an open will. An open will read as infinite (1.) there is no resistance to actually read, while a short will read as no resistance (0.000000000).

An open is a break in the "loop" of wiring. DC power travels from negative to positive through a conductor (your wire) through a component (which creates resistance) back to negative. If you have a break in that loop, it's an open, if you have a conductor or wire, going directly from negative to positive, without any component in between it, that's a short.

Shorts create high current flow, usually higher than what the fuse will allow, so the fuse blows before you have to worry about burning up your wiring, sometimes that theory fails.
 
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