Mark Viii blower not working, not bad harness
A few days ago the heater blower stopped working completely. With car running and heat on 90 I started by jiggling the harness from the relay to the motor, but got nothing. I checked voltage on the two blades coming off the relay and got nothing. I checked power in the plastic connector to the relay, I got nothing.
I checked fuse #9 at the door, and all other fuses at door and under hood...all good.
I swapped the gray case hard button eatc in my 94 to the 98, non-compatible, also the blue case from the 98 doesn't even power up in the 94. Then I realized that when the eatc is disconnected, and key is RUN, it's in emergency high fan defrost mode on the 94. With eatc disconnected in the 98 and key to RUN, there's no fan running.
I ran the self test on the 98 eatc, no DTCs came through.
I bench tested the blower with 12v and it blows high speed.