2004 Chevrolet Silverado, Changing The Mode Actuator

This 2004 Chevrolet Silverado came in with the complaint that the air only blows through the defrost  and will not blow out of any other location. There were codes B0263 and B3770 stored in the HVAC module. The codes refer to mode actuator faults.

To access the actuator, the driver’s side heater floor vent extension has to be removed. There is a single push pin that holds it on.

With the push pin removed from the vehicle the vent extension can be dropped down and pulled off of the main heater- a/c case.

The actuator is located above the driver’s floor vent at the heater case. There are two 8 mm headed screws that hold the actuator to the main assembly. The 8 mm  screws are used if the system has manual controls but has a factory floor mounted center console. If the system had automatic controls or there was not a factory installed floor mounted center console, the screw heads would be 5.5 mm. Also a different actuator part number would be used and the procedure would be slightly different.

The actuator cog gear as it should be installed in the vehicle without the actuator attached.

The old actuator. It has two different numbers printed on the label. 3B1H-19-E616-JA and 00003381A. Neither one of which is the actual replacement part number instead they are the manufacturer’s part number.

In the picture below you can barely see half of the 8 mm headed screw at the lower mounting hole. It is about 3/4″ below the lower right hand corner of the label in the picture below. The second mounting hole is about 1/2″ above the upper right hand corner of the label.

Just a picture to show you the general orientation of the actuator as it is installed under the dash. The picture was taken from the brake pedal area, looking up and towards the center of the dash.

The most needed tool for this job is an 8 mm universal socket. I also used various extensions, ratchets, pliers and a flash light.

I did need an 8 mm wrench to start the upper mounting screw.  The full set of tools I used to change this actuator.

I mentioned this earlier but I just wanted to elaborate a little more. ACDelco is the parts supplier of this part to General Motors and ultimately you and me. Woory is the actual manufacturer that makes this part according to GM specifications.

I point all of this out because Woory does manufacture this part for the aftermarket as well.  However it will be made to the aftermarket parts suppliers specifications and not to the specifications required by General Motors and ACDelco.

If you need to purchase one of these actuators please click here.

3 discussions on “2004 Chevrolet Silverado, Changing The Mode Actuator”

  1. I have my actuator off, but concerned about getting the plastic plate back in correctly. Would it be easier to take off the top of the dash to replace this unit? Just seems almost impossible to get that top screw in. Also, I read somewhere that you should recalibrate the unit after installed.
    Thanks for any answers

      1. Just as a side note. I am having the same problem and came across the site. Got hit by hurricane ida in Louisiana so I really need the ac to blow in the front vents not the defrost.
        If you need to temporarily make it only blow in the front vents. You can take out the 10a hvac fuse(2005 Chevy truck on mine). It will default to blowing out the front. Then unplug the mode actuator wire harness. Then put the hvac fuse back in. Then it will blow only out the front. It’s not a fix but it will also let you know that mode actuator is the problem when you plug it back in.

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