HVAC Mode Actuator Lever installed position

ID Status Date Year Make Model Transmission Type A/C Controls Public/Private
#14565 Closed 1999 Chevrolet Silverado public

Hi: My truck blows good cold air but only from the rear vents, I checked the fuses, I reset the system more times than I care to mention, however I did a visual test on this actuator to see if it would cycle through all the setting, I started the vehicle tuned on the a/c, I then selected turned the selector to blow from the top vents and floor vents still not blowing cold, I then selected both defrost positions and the white lever never moved, I have searched the web over and over trying to find the correct position for the white lever with no results, is there a picture showing the correct position of this lever? In the attachment item 21 and 23 are my concern, I need to know the correct position of these parts installed, as I stated before I think these are not aligned correctly, a picture would save me a ton of cash, can you help me with this issue sir? the control head is item number 3 in the second attachment.


I probably won’t be much help but I need to clear up a few things in order to try. First I need to know if you have an early or late body style truck? 1999 was a split production year.  Next the attachment with items 21 and 23 did not upload properly. I think with some recent updates you can only upload one attachment per reply so you may want to try that again.

Hi: I have the new body style, I opened the attachment and it worked just fine, I sent 2 attachments but only one showed up, now as for viewing the attachment and since you can’t see them let’s go at this differently, my vin number is 2GCEC19T2X1126276, now you can pull up my truck on any GM or Chevy parts store online, the first two numbers in question are mode actuator 52473356 and lever 52474960, the last one is the control head 192448744 with rear defrost and a/c, again I get cold air out of the rear vents and hardly no air from the front and lower vents, again I cycled the mode controls while I watched the mode actuator, the actuator never reached it’s full cycle, meaning the mode actuator stopped half through it’s cycle. all of the actuator’s on my truck are brand new and I have reset them many times with the same results, the BCM is new and flashed twice, the ECM is new and flashed twice as well thinking this may be the problem but both the BCM and the ECM checked out fine, I knw this is a lot but you need to know what I have done and give me your opinion on what steps I need to take to fix this issue, by the way I have had this truck checked out at four chevy dealerships and two of our local automotive shops, actually three automotive shops the third shop would not touch my truck siting bad aftermarket parts, anyway all the other shops plus the dealerships told me my truck’s a/c could not be fixed and I should install an aftermarket a/c unit, but I proved them wrong except for this issue with the mode actuator, can you help. thank you


Parts 12, 13 and 14 are what I see on a GM parts breakdown that I have attached. Are these what you are wanting more information on?

That’s what I’m looking for, however I already have mine installed according to the diagram, so what now?


The best I can do to help is to go step by step through the diagnostic routine if you have the tools and are comfortable with testing which will involve getting twisted up under the dash to access connectors. I will be replying twice because there are two different wiring diagrams. One for a base truck and the other for an uplevel truck.  The difference in the diagrams seems to be that the uplevel truck routes some of the connections through the passenger junction block.

    1. Disconnect the mode door motor connector.
    2. Turn ON the ignition, with the engine OFF.
    3. Probe the ignition positive voltage of the mode door motor with a test lamp that is connected to a good ground.

Does the test lamp illuminate?


Uplevel Diagram

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