Mode door actuator - 2004 Infiniti QX56

Here is a post that may give you an idea as they talk obout checking these a/c codes.

https://www.allpar.com/fix/codes-climate.html

The problem is either the "Mode" door actuator or a stuck mode door. That door is responsible for directing where the air comes out. Locate the mode door and disconnect the actuator. Move the door by hand. If it moves freely, chances are the actuator is bad.

There are no vacuum lines for the HVAC , electroniclly controlled .

Mode Actuator
The mode actuator is an electronic stepper motor with feedback potentiometers. The HVAC control module sends signals to the mode door actuator through the mode door control circuit. Zero volts drives the actuator in one direction while 5-volts moves the actuator in the opposite direction. When the actuator receives 2.5 volts, the actuator rotation stops. A 5-volt reference signal is sent out over the 5-volt reference circuit to the mode actuator. When you select a desired mode setting, logic determines the value of the mode actuator signals. The HVAC control module's software uses this reference voltage in order to determine the position of the mode actuator through the mode door position signal circuit. The motor moves the mode door to the desired position.

Defrost Actuator
The defrost actuator operates the same as the mode actuator. The HVAC control module sends signals to the mode door actuator through the defrost door control circuit. Zero volts drives the actuator in one direction while 5-volts moves the actuator in the opposite direction. When the actuator receives 2.5 volts, the actuator rotation stops. A 5-volt reference signal is sent out over the 5-volt reference circuit to the defrost actuator. When you select a defrost setting, logic determines the value of the defrost actuator signals. The HVAC control module's software uses this reference voltage in order to determine the position of the mode actuator through the defrost door position signal circuit. The motor moves the defrost door to the desired position.

Right side or left ? Electronic Automatic Temperature Control or manual ? Temperature or mode door ?
Temperature Blend Door Actuator - LH Removal and Installation
NOTE: It is not required to install the new LH temperature blend door linkage parts included in the LH temperature blend door actuator service part kit if only the temperature blend door actuator requires replacement and the linkage parts are not broken or binding.
LH temperature blend door actuator and linkage

1. Remove the 2 lower steering column opening cover bolts.

1. Detach the lower steering column opening cover.

1. Disconnect the in-vehicle temperature sensor aspirator hose and electrical connector.

1. Position the instrument panel wire harness away from the LH temperature blend door actuator.

1. Remove the 3 LH temperature blend door actuator screws.

1. Disconnect the LH temperature blend door actuator electrical connector.

1. Remove the LH temperature blend door actuator.

1. Manually operate, and inspect the LH temperature blend door linkage for incorrect placement, binding or damage.

Temperature Blend Door Actuator - RH, Dual-Zone EATC Removal and Installation
NOTE: It is not required to install the new RH temperature blend door linkage parts included in the RH temperature blend door actuator service part kit if only the temperature blend door actuator requires replacement and the linkage parts are not broken or binding.
RH temperature blend door actuator and linkage

1. Disconnect the glove compartment damper from the glove compartment.

1. Remove the glove compartment.

1. Remove the RH lower instrument panel insulator.

1. Remove the RH lower floor console trim panel.

1. Remove the 3 RH temperature blend door actuator screws.

1. Disconnect the RH temperature blend door actuator electrical connector.

1. Remove the RH temperature blend door actuator.

1. Manually operate, and inspect the RH temperature blend door linkage for incorrect placement, binding or damage.
2. Mode Door Actuator - Defrost/Panel/Floor Door
3. Removal and Installation
   NOTE: The defrost/panel/floor mode door actuator can be accessed from below the driver side of the instrument panel.
   NOTE: It is not required to install the new defrost/panel/floor mode door linkage parts included in the defrost/panel/floor mode door actuator service part kit if only the mode door actuator requires replacement and the linkage parts are not broken or binding.
   Mode door actuator and linkage
   1. Remove the 3 defrost/panel/floor mode door actuator screws.
   1. Disconnect the defrost/panel/floor mode door actuator electrical connector.
   1. Remove the defrost/panel/floor mode door actuator.
   1. Manually operate, and inspect the defrost/panel/floor mode door linkage for incorrect placement or damage.
   Mode door actuator linkage only
   
   1. Remove the mode door linkage.
      1. Depress the tab and remove the panel door lever.
      1. Remove the floor/defrost door intermediate lever screw and floor/defrost door intermediate lever.
      1. Pull straight outward to remove the floor/defrost door lever.
   Mode door actuator and linkage
   
   1. NOTE: When installing the mode door actuator, make sure that the panel door lever and floor/defrost intermediate lever are correctly aligned with the mode door actuator cam.
      To install, reverse the removal procedure.

Air Distribution
The HVAC control module controls the distribution of air by the use of a defrost actuator and a mode actuator. The modes that may be selected are:
?€¢
Defrost

?€¢
Defog

?€¢
Panel

?€¢
Bi-Level

?€¢
Floor

The mode and defrost actuators are connected to the mode and defrost doors by a cam type linkage system. Depending on the position of the door, air is directed through the HVAC module and distributed through various ducts leading to the outlets in the dash. If the HVAC control module detects a fault with the mode or defrost doors the HVAC control module will try to drive the actuator for a predetermined amount of time, to defrost, which is the defaulted position for the mode and defrost door actuators. When the mode switch is placed in the defrost or defog positions the A/C is commanded on and the recirculation door is moved to the outside air position to help reduce window fogging. A/C is available in all modes and recirculation is only available in the panel and bi-level modes.
Circuit Description The following DTCs are for the HVAC door actuators: ?€¢
B0248 is for the defrost actuator.
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B0263 is for the mode actuator.
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B0408 is for the left air temperature actuator.
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B0418 is for the right air temperature actuator.
The HVAC control module controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator consists of a stepper motor, a logic circuit, and a potentiometer. The potentiometer inside the door actuator allows the module to monitor the current position of the actuator drive shaft. The logic circuit inside the actuators receives control signals from the HVAC control module and controls the internal stepper motor. When a door positional change is required, the HVAC control module calculates a commanded door position. The module compares the commanded door position to the actual door position and determines the needed direction of motor rotation. The module applies a signal voltage to the door control circuit that is an input to the internal logic circuit of the door actuator. A 5 volt signal increases the door position. A 0 volt signal decreases the door position. When the commanded door position is equal to the actual door position, the HVAC control module sends a 2.5 volt signal to the door actuator and motor rotation stops. The ignition 3 voltage circuit provides source voltage to the logic circuit. The module provides ground to the actuator logic circuit through the low reference circuit. I would start by having the HVAC control module checked for DTC'S -diagnostic trouble codes First . Then check the system by using scan tool data . 1
Did you perform the HVAC Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - HVAC Systems - Manual

2

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command the appropriate HVAC door actuator ON and OFF while observing the corresponding Door Actual parameter.

Does the scan tool indicate that the value of the appropriate Door Actual parameter changes?
Go to Diagnostic Aids
Go to Step 3

I would

The blower motor is probably not working.

The mode door actuators are reversible, 12-volt direct current (DC) servo motors. The heating-A/C systems on this vehicle use two mode door actuators. One for the panel/floor-air door and one for the defrost-air door.

Both the defrost door actuator (1) and the panel/floor door actuator (2) and the are located on the driver side end of the HVAC housing (3), close to the dash panel.

All actuators (1) are interchangeable with each other. Each actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle (2). Each actuator also has an identical output shaft with splines (3) that connects it to its respective door linkage and three integral mounting tabs (4) that allow the actuator to be secured to the HVAC housing. The mode door actuators do not require mechanical indexing to the mode-air doors, as they are electronically calibrated by the A/C-heater control.
OPERATION

The mode door actuators are connected to the A/C-heater control through the vehicle electrical system by dedicated two-wire leads and connectors of the HVAC wire harness. The mode door actuators can move the defrost-air door and the panel/floor-air door in two directions. When the A/C-heater control pulls the voltage on one side of the motor connection high and the other connection low, the mode-air door will move in one direction. When the A/C-heater control reverses the polarity of the voltage to the motor, the mode-air door moves in the opposite direction.

When the A/C-heater control makes the voltage to both connections high or both connections low, the mode-air door stops and will not move. The A/C-heater control uses a pulse-count positioning system to monitor the operation and relative position of the mode door actuators and the mode-air doors. The A/C-heater control learns the mode-air door stop positions during the Actuator Calibration procedure and will store a Diagnostic Trouble Code (DTC) for any problems it detects in the mode door actuator circuits.

The mode door actuators are diagnosed using a scan tool (Refer to 28 - DTC-Based Diagnostics/HVAC - Diagnosis and Testing).

The mode door actuators cannot be adjusted or repaired and must be replaced if inoperative or damaged.

Same as first set of instructions:
Mode Valve Actuator Replacement - Left Side Removal Procedure

1. Remove the floor air outlet (center) from the vehicle.
   
2. Remove the vacuum connector.
3. Slide the actuator off the mounting bracket in order to remove the actuator.
4. Rotate the mode door linkage down.
5. Rotate the actuator (2) so that the actuator linkage slips off the post on the mode door linkage.
   Remove the actuator linkage from the mode door linkage

I would look at the air blend doors first, it sound like they are not working or your control in the dash is not working send a signal to them. they work by changing the air from hot to cold or in between.

Avalanche, Sierra And Silverado

1. Remove the floor air outlet duct extension (1) from the floor duct (2). Remove the floor air outlet duct extension (1) from the floor duct (2)
2. Disconnect the electrical connection at the blend door actuator (10). Blend door actuator and related components
3. Remove the blend door actuator mounting screws from the HVAC module.
4. Remove the blend door actuator as an assembly with the actuator cam. Remove the blend door actuator mounting screws from the HVAC module

To install:

1. Install the blend door actuator as an assembly with the actuator cam.
   1. Line up the heater/defroster valve lever with the blend door actuator cam slot.
   2. Line up the A/C valve lever with the blend door actuator cam
2. Install the blend door actuator mounting screw to the HVAC module.
   1. Tighten the blend door actuator mounting screw to 14 inch lbs. (1.6 Nm).
3. Connect the electrical connection at the blend door actuator (10). Blend door actuator and related components
4. Install the floor air outlet duct extension (1) to the floor air duct (2).

C/K Series

1. Disconnect the electrical connector to the mode actuator that is located on the left side of the air distribution case.
2. Remove the screws.
3. Remove the adjuster links from the control lever.
4. Remove the mode actuator.
5. Adjust the mode actuator by completing the following steps:
   1. Connect the electrical connector to the actuator.
   2. Turn the ignition switch to the RUN position. Allow the self-positioning of the actuator.
   3. Turn the ignition switch to the OFF position.
   4. Remove the actuator from the electrical connection. Blend door actuator-C/K Series

To install:

1. Install the mode actuator.
2. Install the screws.
3. Install the adjuster links to the control lever.
4. Connect the electrical connector.
5. Test the circuit operation