98 Deville Head/AC blend issue

[clauritzen]

I am working on my dad's deville and with the AC on it only blows cold out of the passenger side and you get heat from the drivers side. Any ideas on what is causing the issue or what the fix is?

Thanks!

[Blue Bowtie]

If the glove compartment liner is removed, the area just forward of that contains the ventilation ducting and some controls. There is a stepper motor actuator on the upper right corner of the ducting which operates the heat/cool blend door for the passenger side. The linkage rod can be disconnected from that to determine if the blend door is stuck or bound in place or if it moves freely. With the linkage disconnected the passenger side zone controls can also be operated to maximum heat and cool to determine if the actuator is moving properly.

If everything appears to be moving freely and functioning, the stepper motor can be recalibrated to the controller by cycling the ignition power on for at least three minutes while the main AC controls are in AUTO position. The controller should cycle the stepper motor to the ends of travel and then position it to the appropriate place for the commanded temperature.

Chances are that one of those two items is the reason for the cool air only on the right side.