99 Concorde HVAC Question

I have a Concorde 1999............has a electronic display/controls for the
HVAC.....blower motor rotary/speed switch is part of the underlying control
board.
All works with exception that fan is on high all the time regardless of
rotary switch position. I have seen posts that say a common problem is open
resistor and possibly worn motor wrecking the resistor. These posts all
refer to the fan only working on high "position". Mine is on high regardless
of switch position. Even when HVAC switched to off. Resistor? Something
else?

 

I can't say for sure about a 1999 Concorde (second generation) but on
the first-generation Concordes, the electronic HVAC system doesn't use a
simple resistor for fan speed control. There is a module under the dash
near the fan motor that receives the commands from the control head and
then regulates power to the fan motor (either a linear power amplifier
or a pulse-width modulator, I never bothered to test and see but its got
some power transistors on it). When that sucker fails, you get (you
guessed it) high fan all the time. IIRC, it was order of $50 to replace.

 

Thank You!! That is why I posted like I did. If there was a resistor issue
it would shut off when hvac off. I could see the small gauge wire on the
back of the board and knew there had to be something else. I suspected there
was a motor control down the line. Truth is, it is my neighbors kid next
door ( car ) and their broke. I told him i would see what I could do. Thanks
again.

 

sounds like the power module for the blower motor is bad if u have the manual
havc controller then u have a blower resistor but the auto system has a power
module
which is a pulse width modulation driver and is more costly to fix