Rick's Free Auto Repair Advice

Dodge Ram Mode Door Actuator

Fix Inoperative Dodge Ram Mode Door Actuator

Explanation of the Dodge Ram Mode Door Actuator problem

The Dodge Ram Mode Door Actuator operates the mode door in the heater box. The mode door is what changes the direction of the air coming out of the vents. Moving the door to different locations changes whether the air comes out of the defrost, floor, dash vents or a combination of both.

The vehicles listed below use an electric motor mode door actuator. These models use TWO mode door actuators; one to control dash vents and floor and the other to operate the defrost mode

2008 Ram 1500 3.7

2009 Ram 1500 3.7

2010 Ram 1500 3.7

2008 Ram 1500 4.7

2009 Ram 1500 4.7

2010 Ram 1500 4.7

2008 Ram 1500 5.7

2009 Ram 1500 5.7

2010 Ram 1500 5.7

2008 Ram 2500 5.7

2009 Ram 2500 5.7

2010 Ram 2500 5.7

How a mode door actuator works

The HVAC control head sends power to the defrost mode door actuator on the

mode door actuator

Mode door actuator

dark blue/orange wire and ground on the dark blue/light green wire. The panel/floor mode door actuator is powered on the dark blue wire with ground on the dark blue/light blue wire.

Test mode door actuator

Disconnect the C1 connector at the HVAC control head. Check for battery power on pins 14 & 15. Next, check for good ground at pin #1.

mode door actuator

HVAC control head connector pinout

Next check for digital bus voltage on pins 12 & 13 of the same connector. One of the wires should have approx. 2.5 volts.

Before you replace the mode door actuator

Replacing the mode door actuator is easy. Just remove the screws and actuator and line up the splines on the new actuator with the splines on the mode door. Then reconnect the connectors.

defrost mode door actuator

Defrost mode door actuator

mode door actuator

Panel floor mode door actuator

Fix U0164 trouble code

Sometimes the HVAC control head will lose communication with the new actuator and set the U0164 trouble code. Do not freak out. This is an easy fix


Disconnect the positive and negative battery cables and touch them together for 15 seconds. This drains the capacitors in all the control units and forces a reset. Then reconnect the battery cables and the problem should be solved

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Posted on by Rick Muscoplat

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