My blower motor only seems to run very weak on ALL switch settings.
Verified power on plug at motor and can visually see squirrel cage spin when dropped and connected to power.
Replaced blower motor resistor. Still only runs at very low speed with just a whisper of air from vents at all speed settings.
Could it be the speed control switch? If so, how to test if bad?
Could it still be a bad blower motor?
Could it be a bad NEW resistor? If it's a bad resistor, how to check if resistor is really bad?
Ohmed out all pins on old resistor and all have resistance in varying degrees, with no opens. Didn't know which pin is #1, but L to R and R to L all have no opens!
....Any insight would be appreciated!

 

A good starting point would be to remove the blower motor and apply power to it and see what it does.
If it runs slow in your hand , it needs to be replaced. If it runs fast and good in your hand check power and ground to motor which come from the blower switch.
They did have problems with the switch wiring getting hot and corroding , that might also be a good place to start. If that was the problem a kit with plug and switch used to be available.

 

Hanky,
My question described the fact that I tested the fan and it ran slow. I guess "slow" is a relative term. After trying a resistor without luck, I moved on to the panel switch. With new switch in hand, I accessed the rear of the panel.
EUREKA!
Somehow the switch connector plug had come off of the mounted switch.
Reattached, and now ALL speeds of blower motor work.
Returned all "new" parts back to Amazon for refund.
I really appreciate your input!
Sometimes things are just too simple to comprehend!
This case is a good exampke!

 

I hope you get an opportunity to read this post BEFORE returning the switch and plug.

You made a temporary repair , those plugs don't just fall off, they fit quite tightly to the terminals on the switch.

The high current draw of the blower motor was responsible for the contact overheating and if you look carefully, you will see signs of excessive current draw..Sometimes you will see where the back of the switch has even melted due to excessive heat.
The motor should be replaced as well as the switch and plug.