Aaron,
I tested my fan from the battery.
I believe I had a bad relay or sensor one time and I drove for weeks with the AC turned on.
- The fan runs 100% of the time with the AC switched to the ON position.
- Also, you can unplug the wire from the peak of the thermostat housing -- the fan will also run 100% of the time.
If it's a sensor, the fan will run in either case.
If it's a relay, the fan *may* not run in either case.
.