Folks, Have a 99 Ram 2500 Diesel and have replaced both the blend door motor and the AC/Heater control unit. My issue is that the blend door motor will NOT turn when it is plugged into the harness by the blend door motor. The blend door motor will turn when it is on the bench and has a 9 volt battery connected to it. Once it is plugged into the harness plug it does NOT turn. I have the wiring diagram and will attach it.
I am getting power out of the BLUE wire at the end of the plug as it is supposed to be hot from ignition. I am not getting any power out of the yellow wire which I believes tells the blend door when and how much to turn based upon where you select the hot / cold dial. Moving the hot/cold dial does not power the yellow wire at all.
I have checked continuity of the wires going from the plug that connects the AC/Heater control unit to the end of the plug that goes into the blend door motor. There is continuity on all the wires. I picked up two blend door motors from a salvage yard along with a replacement AC/Heater control unit at a salvage yard so I can't say for certain they work 100%.
Does anyone else have any experience in troubleshooting the blend door besides the heater treater part that is know to fail? That is not my issue as the motor itself is not turning when plugged in. I have not found anything relevant on the net that deals with testing the blend door motor beyond putting power to it and see if the motor turns. There is a circuit board in the motor unit as well, so that may be faulty.
Any suggestions would be appreciated!