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98 mustang gt... So, heater blower motor doesn't work. No fuse diagram (don't think the internet one i found s correct) but all fuses i checked under the dash seem good.

No voltage at heater fan switch or at fan itself. Powered fan off battery and works fine. Any thoughts? Bad wire somewhere? Just stopped working..

wondered if anyone had an accurate wiring diagram? wondering if there might be a fusible link somewhere in the circuit. thanks
 

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you answered it
 

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Just wondering. Have you considered the possibility of a bad blower motor resister? These often rust out due to the high humidity inside the AC flow. Very common problem.

It's also fairly easy to remove the ballast resister and jump across it. If this make the blower run on high, then the diagnosis is confirmed.

Note, in the interest of good trouble shooting it's wise to also confirm the ability of the fan's ground to carry a current. Use a test light that will "load" the circuit. The blower motor ballast resister is down stream of the blower motor. So any problem with the resister will also show up in the ground test at the motor.

WVE/AIRTEX/WELLS 4P1367
https://www.rockauto.com/en/moreinfo.php?pk=1191587&cc=1304480&jsn=463

Note2, IF there's no power at the Heater control assembly BR/O wire, then either:
  • I/P fuse #17 is bad
  • There's no power into I/P #17
  • Or there's a wiring fault between the fuse and the control assembly. Note, be sure to use a KNOWN good ground for testing.
 
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