Blower Resistor Wiring
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From: Jackson,NJ
Blower Resistor Wiring
My blower stopped working a few weeks ago. I replaced the blower resistor a couple of weeks ago and this fixed it. I read you should replace the electrical harness as well. The old wiring had corrosion on it as well. I got this part off of amazon /Dorman-973-307-Blower-Resistor-Harness. I was careful to do one wire at a time since new one is not color coded. I used the crimps that came with it. Now blower back to not working. I checked my connections all are tight. Any ideas? This is on an 08 Ranger. it got to dark to try using a volt meter. What should I look for when I can have time and daylight on volt meter? Thank you
2008 wiring diagram below
The Blower motor gets 12volts when selector is in ANY position except OFF, this closes Blower Motor relay in engine fuse box
The Fan Speed switch is the GROUND for the blower motor
You have to keep that in mind when testing with voltmeter
So Resistor block routes Ground thru the 3 resistors, all 3 resistors is low, then 2 resistors is med 1, then 1 resistor is med 2, then no resistors is High
High by passes Resistor block
So if High doesn't work then check Blower Relay or Blower fuse in engine fuse box, it is possible the GROUND in the cab for the fan switch has come loose but a real long shot, and this wouldn't effect low or mediums, because they use a different ground, as seen on diagram
If high does work, but not low, and mediums, then resistor block wiring is most likely issue, check its Ground, pin #3 in diagram, if this wasn't good then no lower speeds would work
The Blower motor gets 12volts when selector is in ANY position except OFF, this closes Blower Motor relay in engine fuse box
The Fan Speed switch is the GROUND for the blower motor
You have to keep that in mind when testing with voltmeter
So Resistor block routes Ground thru the 3 resistors, all 3 resistors is low, then 2 resistors is med 1, then 1 resistor is med 2, then no resistors is High
High by passes Resistor block
So if High doesn't work then check Blower Relay or Blower fuse in engine fuse box, it is possible the GROUND in the cab for the fan switch has come loose but a real long shot, and this wouldn't effect low or mediums, because they use a different ground, as seen on diagram
If high does work, but not low, and mediums, then resistor block wiring is most likely issue, check its Ground, pin #3 in diagram, if this wasn't good then no lower speeds would work
This post made me finally go fix mine a few minutes ago. Been meaning to for months now. I wrapped sandpaper around a mini-screwdriver and kept sanding the rust off of both sides of the male terminals inside of the resistor unit. I'd already replaced my wiring harness connector a couple months ago with a better looking unit from a parts truck as well as the resistor pack. Filled it up with dielectric grease and no-go. Wiggled the connector into another position and it worked on all speeds. Looks like I've got a little more sanding/cleaning to do on my connectors/terminals... but I ran out of daylight.
GB :)
GB :)
Heads up on dielectric grease, it does NOT conduct electricity, which is the point of using it on electrical connectors, but not INSIDE the connectors, if you get it on the metal contacts then..................it does what its suppose to do, prevents water from coming in and PREVENTS electricity from flowing
Thread Starter
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Joined: May 2010
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From: Jackson,NJ
Update
i came out at lunch and blower worked on all speeds. The only think I can think of hit a bump or something on way in. The ride home 30 mins was fine as well. Thanks for the info and reply RonD!
Heads up on dielectric grease, it does NOT conduct electricity, which is the point of using it on electrical connectors, but not INSIDE the connectors, if you get it on the metal contacts then..................it does what its suppose to do, prevents water from coming in and PREVENTS electricity from flowing
I use it heavily in everything, from all sorts of bulbs, connectors, and even plug wires. In and on the terminals. Never the slightest problem.
The male terminals on my resistor pack were dark brown with very heavy rust so that's where my continuity/conductivity issues lie.
GB :)
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