Took a look at shunts in action. This is with fan speed on low, t-switch full CCW, and resistor out of duct. Takes a few seconds for thin coil shunt to close once AC is turned on. Bear in mind there's no air passing over this to cool it.
Also looked at speed 2 and 3. Shunts did not move. Opened both gaps to just over 1/16" and cleaned contacts with emery. Have no idea if this gap is on, off, or near spec. Will see how it works.
Next on today's menu is hunt for vibration coming from evap area. Is noticeable on speed 2 at idle only (as in stopped at red light). Not noticeable when driving due to drive noise. Speed 1 is fine. Speed 3 there's too much air noise from vent to hear it.
Took blower housing off - (camera battery dead now) and checked to make sure it was blowing in right direction
. Yes. Checked clearance again. OK. Ran at different speeds... it's quiet. Picked up housing when running... and... Unbalanced blower. Missing this fact when checking the motor spin (without touching it) on prior install is error to be added to list.
Even with potential problem found, thermo probe in core of evap is isolated from evap as capillary travels from core to exit of plenum, harder stand offs are placed between blower housing and evap, capillary is isolated from outside of plenum as it travels toward cabin. Idea being to squelch vibrations coming from any of these parts/areas.
Result - Vibration noise is... much worse now!
Next move - Hunt for balanced blower.