Chrysler Repair: 1999 Intrepid 3.2 SE :ATC no digital readout, heat duct, headlamp switch

Question
ATC - The LED display does not ligt up. The fan works and heat is produced, but because the LED is not functioning, it does not appear to be on. You cannot see the temperature or what what heat duct options you have chosen.

Answer
Hi Bruce,
The manual doesn't show their to be a separate circuit for the digital readout. If its intensity has a unique control pot then I would look into the pot and its wires after removing the control unit. You can do that by removing the center bezel and the wires that are on its back side and finally remove the control itself from that bezel and check it for any obvious problems with the digital intensity adjuster. There is a variable brightness signal from the panel dimmer circuit of the headlamp switch which comes to the controller on pin 4, but I believe that controls the light level of the control panel, not the digital readout itself. But you could measure the voltage on the wire at pin 4 and see if it is reading and whether it varies if you adjust the brightness of the dash by using the headlamp control switch pot for variable brighness levels.  So you may have to troubleshoot the control unit without any help from the manual.
Just in case, check pin 10 of the plug to see that it has 12v when you have the ignition 'on' as that is the overall power to the control unit. Other than that, check the circuit board for the LED readout and look for cold solder joints that might need to be re-heated to regain the power for the LED.
Roland