Blower fan issue

Tiny
SCOTT PEARSON
  • MEMBER
  • 2003 DODGE RAM
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 169,000 MILES
Had issue with only high speed working and only vents, figured switch and replaced. No change researched and replaced resister. Understand problem with only vents and will address that myself. The issue is I have fan working in positions one, three and four. Does not work on position two. Any insight?
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Friday, March 3rd, 2017 AT 3:18 PM

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Tiny
CARADIODOC
  • EXPERT
Do you have a computer-controlled heater system, or are your mode doors actuated with common-sense switches and push buttons?
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Friday, March 3rd, 2017 AT 3:54 PM
Tiny
SCOTT PEARSON
  • MEMBER
Issue is fan not working on only position number two, runs the same as position one. Position three and four run at proper speeds. One runs at proper speed two runs same as one. Mode door to change from vent to defrost and floor heat actuator shaft broken already planning that fix, not the issue. Replaced HVAC dash switch assembly and resister. This gave me back multiple fan speeds and further research revealed broken mode door. This is where I stand. All fan speeds work as they should except number two.
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Saturday, March 4th, 2017 AT 12:35 PM
Tiny
CARADIODOC
  • EXPERT
I am using a wiring diagram for the manual system. The light green wire is fan speed two between the switch and the resistor assembly. If there were to be a break in that wire, the fan should not run at all on speed two, however, the drawings are not always correct when it comes to showing the internal switching. If your switch has an "off" position, does that work? Some systems only have speed one as the lowest setting. In that case, that circuit is always on, then the other speeds bypass speed one. A break in any other circuit would make the fan run in the lowest speed.

Unplug the connector from the resistor assembly, then measure the resistance on each wire to ground. You should find close to zero ohms on only the black/tan wire in the "high" position. The other wires should read open circuit. You should find zero ohms to ground on only the light blue wire in the second highest position. Zero ohms on only the light green in the third highest position, and zero ohms only on the tan wire on the slowest position.

Measure the resistance between the light green and the tan wires.
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Sunday, March 5th, 2017 AT 1:41 PM

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