2004 Chevrolet Impala, No Heat Driver’s Side, Code B0408

This 2004 Chevrolet Impala came in with the complaint that there was no heat on the driver’s side of the car. It could very well have been the reverse, no a/c on the driver side as the problem turned out to be a faulty driver’s side blend air door actuator assembly. There was a code B0408 stored for the that actuator. If you do not have a way of checking for codes, the actuator should be watched to see if it responds to command inputs. When there is a no or poor heat condition the coolant level should always be checked first.

To access the actuator the lower dash cover has to be removed but first the cover on the left end of the dash has to come off.

Then the driver’s side hush panel.

There may be a couple of screws along the lower edge of the panel. After they are removed the cover will pull off the dash and the trunk release switch can be disconnected if present.

Four 10 mm headed screws are recessed behind the metal knee bolster and there are several 7 mm headed screws around the exterior of the panel.

You can now see the actuator in the center of the following picture. The white label is easily visible. Testing is difficult at best but here is what needs to be done if you do not have a scan tool that will interface with the system. Back probe the yellow wire and the dark blue/white wires with a voltmeter. There should be 0 volts for a stationary command. There should be a 12 volt positive for a commanded movement and a negative 12 volt reading in the opposite direction. Note that the code may have to be cleared before the control head will make the commands. Use a scan tool, disconnect the battery or remove the DIC/RKE fuse for at least 60 seconds.

This is what the actuator looks like out of the vehicle. The screws holding the actuator to the case should have 5.5 mm heads. To order this actuator please click here.

After replacement of any of the actuators a recalibration procedure needs to be performed. It is very simple though. Turn the ignition off, remove the DIC/RKE fuse from the right / passenger side, interior fuse box. It is a 10 amp fuse. Leave the fuse out for at least 60 second. Install the fuse and turn on the ignition. Do not touch the a/c controls for at least 60 seconds. switch the key off for at least 10 seconds and the recalibration will be complete when you restart the engine.

76 discussions on “2004 Chevrolet Impala, No Heat Driver’s Side, Code B0408”

  1. My husband replaced the actuator just a few days ago for a different problem we were having. Anytime we had the ac or defroster on, any movement to turn it to a different setting or turn it off would cause a constant tapping. Very annoying. Anyway, he replaced the actuator but just a few days later the heat stopped on the drivers side and only blows cold air. Would not recalibrating cause this to happen or is the actuator bad?
    2009 Impala

  2. The first two things to consider are is there an adequate supply of engine coolant to the heater core. The other is the driver’s blend air door actuator responding to commands from the control head. So check the coolant level of a cold engine and correct if needed. Then observe the actuator and see if it responds to commands. You may need a small mirror and flash light to do this.

  3. I have a 2005 Chevrolet Impala that has heat on the passenger’s side, but no heat on the driver’s side. I replaced the actuator and recalibrated. I turned on the car and heat was flowing from both sides. I was happy and my wife was impressed. The next day, the problem returned. I get heat from the passenger’s side but no heat from the driver’s side. I tried recalibrating again by pulling out the DIC/RKE fuse from the passenger’s side, but still no heat on the driver’s side. I even pulled off the battery connections for recalibration, still no heat on the driver’s side. Why would it work for only one day?

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