This 2004 Chevrolet Tahoe came in with the complaint that the air on the driver’s side would change from cold to hot while driving down the road. When it shifted to hot the customer could not get it to turn back cold. Sounds like a faulty air mix actuator to me. I checked codes and sure enough there was a code B0408 for the left air temperature actuator. I checked the commanded position versus the actual position and there was a large difference in the counts. This is only important if you have a scan tool that will access this system. There are other tricks that can be used to test that I will show later. The driver’s or left air mix actuator is located on the lower passenger side of the dash. If present the hush panel has to be removed. This one is easy because there is no floor mounted center console. If you have a floor console please see the information at this link to see how to deal with one screw.
I removed the four 7 mm headed screws and pulled the panel out of the way.
I knew I was changing the actuator, so I disconnected the wiring harness connector and removed the two 5.5 mm headed screws
Then the actuator simply pulls down. There may be some resistance if the actuator is at the full stop position.
Slide the new actuator into position, install the mounting screws and reconnect the wires. After this was done I recalibrated the actuator with my Tech 2 scan tool. If you do not have a scan tool you may disconnect the battery for one minute. Reconnect the battery and start the engine. The key point is DO NOT TOUCH the a/c controls for at least one full minute. Actually, I prefer to wait 4 minutes because I remember reading that a few years ago and the extra time does not hurt anything. After one full minute turn the ignition off. Restart the engine and check the door operation.
Proper operation can be seen in the data stream in that the commanded and actual positions are at nearly identical counts.
To do testing with a voltmeter at the harness connector you will need to test the following. Check for ignition power on the brown wire. If power is not present check the HVAC 1 fuse in the left interior fuse box. Check for a 5 volt reference signal on the light blue/black wire. All of the next tests must be done with the harness connector plugged into the actuator. The yellow wire is a low reference wire from the control head (ground, internal system not chassis). The light blue wire is the position signal wire from the actuator to the control head. If the actuator will move the voltage will change up or down depending on the movement of the actuator (between 0 and 5 volts). The dark blue wire will have basically three different voltages that are important. 5 volts is a signal to increase the door position, 0 volts is a signal to decrease the door position and 2.5 volts is a signal to hold the door position. So with that information turn the ignition on and touch the black lead of your voltmeter to the yellow wire. Touch the red lead of your meter to the brown wire and check for a reading of battery voltage. Next touch the red lead to the dark blue wire and check for either 0, 2.5 or 5 volts depending on command. You will probably need an assistant to adjust the temperature control for the driver’s side.
Something else you need to know. If you buy a new actuator make sure the part numbers match. At the time of this writing the aftermarket (non dealer) application books are incorrect. You have to buy an actuator for the passenger side to get the correct actuator for the driver’s side. Crazy but true. I cannot think of the number of actuators I have changed that have already been replaced by others. If you install the wrong actuator, it will rotate to a full stop and never move again.
This is the box that the actuator I installed came in and the numbers on the actual parts matched (52402588). The short number is 15-72971. Long number 89018365 and it is listed as the passenger or top air mix actuator. To order this part please click here.
Did you recalibrate the actuators? Are you sure that actuator is making the noise? it is more common for the mode actuator to make a ticking noise than all of the others. Also keep in mind that the recirculation actuator is located in the same general area as the passenger temperature door actuator. Also just to be clear the passenger side temperature actuator is located on the passenger side of the dash on Top of the heater-a/c case. The actuator on the Bottom of the case, on the passenger side is the driver’s temperature door actuator. Do you happen to have a fault code number?
I have replaced the passenger side temperature control actuator on my 2005 2500 Suburban and in the full hot position I will occasionally get a knocking noise. If I move the temperature control lever about 1/4 of the way off of full hot the noise stops. This is the same thing the previous actuator was doing. It’s an intermittent problem that happens while driving and sometimes at startup. What could be causing this?
Since all areas are being affected by no heat the very first thing to do is to check the engine coolant level. No or low coolant level equals no heat. Most vehicles and GM trucks in particular are designed to “alert” the driver of a coolant issue before the engine temperature is affected. The heater cores are the highest point in to cooling system and the first to run dry if the coolant level drops. If no issue is found there I would suggest a recalibration of the actuators. Still no solution, check the junction block connectors at the passenger side of the dash.
Hi Sparky,
First – thank you for all the helpful information. I will be going in just a few to make the paypal donation. Your site it great!
I have the same issue as this post. 2004 Tahoe, Blows HOT hair when set to cold on drivers side only. 16 months ago (just before extended warranty ended)Chevy replaced the “Left Side Temperature Actuator” – same part number you have in your illustration. It fixed the problem for all of about 6 months. I was just starting to read up on it, when we had a few cold days in Texas. Now the heater is blowing COLD air. Odd thing is – cold in front driver/passenger and rear. I haven’t been able to test the A/C in rear right now (used to work) because of course if it is cold outside the A/C always blows cold air like a champ. So odd. Anyway – I guess my question is: do you think everything is related? I was just about to replace the Actuator myself this time, but now worry that the one part won’t fix the what is now, going into winter, a more pressing issue of the heater.
Thanks for any thoughts!
Maria
If you still have access to a scan tool I would start by checking codes and data for the actuators. I would then follow that up with checking the interior and exterior temperature sensor readings. You may also want to do a recalibration using the scan tool. Remember to not touch the a/c controls during the recalibration process. also remember that if a hard fault code is set, the command to the actuators is a stall command. This happens in the first one to two minutes of engine start up.