I think I have tested and isolated the problem, but I thought I would verify
before I go out and buy parts.
Several months ago, my fan speed on my heater control lost the second from
lowest setting. Basically, low and second from low would operate the
heater(A/C) blower at the same speed. The third and high settings worked as
expected. This past weekend, the third setting now operates at the same
speed as the bottom two and only the highest setting is different.
I went under the passenger side of the dash and pulled the connected from
the lower motor and the blower resistor.
There is power going to the blower motor at all four fan settings. When the
switch is set to high, there is no power at any of the four terminals on the
blower resistor connector (not the resistor itself).
At the three lower settings, power is present at the same single terminal of
the four. It is one of the central terminals. Essentially, the switch does
not seem to have any effect until it is set to high.
It seems a reasonable conclusion that the switch or the associated wiring is
faulty. I plan to replace the switch.
Am I on the right track or should I be looking to something else first?
Reply by email and to the group if you don't mind.