Hello, Since this is an electronic control head the diagnostic are performed using a scan tool that can access and actuate the motors - like the DRB we use at the dealer.
You can try to reboot the system. Disconnect the battery for ten minutes and then reconnect and start the engine . This will force the a/c to recalibrate itself and many times this will cure the problems. If it does not you will need to scan for faults and then proceed with the repairs. I hope this helps. Please reply if you need more help or info, Thanks Scott.
When the battery is disconnected it does reset for a short period of time (1-2 days) then the problem starts again. No codes show up when I scan for faults.
So what I am looking for is how to test the control head. The motor that operates the blend doors is just your basic 2 wire dumb motor. The are either in operation or not. The doors and linkage do not have a mechanical stop so I assume that when the system has been reset the control head is designed to send a predetermined signal (period of time) to the motor which should perform the function that is determined by the position of the knob on the head. Is this how it works? If so, how do you test it?
Hello, The a/c system and control head operation is diagnosed using the DBRlll scan tool . I am not aware of any other type of scan tool you could use.
The motors are calibrated by measuring a increase in current when the door stalls against the normal stop. The computer counts the revolutions required to span the distance between the stops and then determines the number of counts to set a specific mode thats been selected. The memory of the a/c is not adjustable.
common problems are binding doors and linkages. Any thing that can cause the motor to stop will be considered a "stop" and the "span " will change - thus the door positions are inaccurate if a door stalls before fully opened or closed. Debris like pens or air freshners can stall a door. Many times the door linkage is broken and the motor will not stop or get bound up when reversed . We replace a lot of doors and few control heads for these type of problems .The door will stall and the motor continues to drive it towards a remembered stop and the linkage or arm breaks . And the doors can break at the normal stop- because the motor overdrives the stop and the strong motor breaks the door at the normal stop before it stalls out .
again , To test the a/c controil head a sscanner is needed.
All the motors are the same and can be swapped.
I hope this helps . if you need more info, please reply, Thanks , Scott