i have a 98 xj, i recently changed my heater core. Did the whole thing, pulled out dash, pulled case, tried to be as careful as possible. Put new core in, put it mostly back together, enough to test.
Long story short, fan blower don't work. I changed out the resistor, swapped relays, checked fuses, checked wires, harness, made sure nothing was loose, broke or unplugged . I have a multi meter, but not very good with it. I also tried 3 different switch panels, still nothing.
Other guys say i have a bad ground or broke wire.
If i cut the 2 wires to the fan, and jump it, fan works fine.
Since i swapped relays, i turn on switch & relays buzzes.
I went back to old resistor, & old relay, still nothing.
This is driving me nuts!!!!
Yeah the jeep does run fine.
I also noticed: radio don't work, gauge cluster works a little.
Gauge cluster been acting up for some time, cause oil pressure goes to zero while driving, & either speedo or tach don't work either.
beyond that jeep is fine. I also have codes withe the NSS.
But that is unrelated to fan.

 

Here's the HVAC Blower schematic, and the ground network.

Note that G108 is the ground(s) for the HVAC and the instrument cluster and radio.

G108 is located under the dash on the driver's side (buried deep in). There are two ground studs there so some circuits may have a good ground where others may not.

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with all that gnd wire connections ,is there no wire back to batt gnd?
do they depend on a chassis bolt for all grounds?

 

Here's the main chassis to battery ground cable. Many circuits in the body have their own ground; all of which have to pass through the fender to battery ground cable.



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