AC problems

Discussion in 'Domestics' started by Cristino Cabrera, Jul 17, 2017.

  1. Cristino Cabrera

    Cristino Cabrera Newbie

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    Please fill out the following to ask a question.

    MAKE:Chevy
    MODESilverdao 1500
    YEAR
    :2012
    MILES:47,000
    ENGINE:5.3
    DESCRIBE ISSUE....When I turn on the fan on my truck's AC unit and while it's in recirc mode cold air starts to blow as if the AC is actually on. Also whenever I switch the vent to defrost or defog I only get air blowing out from the vents facing the driver and passenger sides only. I can never switch the air to blow out from the windshield and floor areas via the AC control panel switch. I was initially going to bring my truck to the Dealer to have them do a diagnose but they were asking $130.00 just for an initial diagnose. Please help.
     
  2. nickb2

    nickb2 Wrench. I help when I can

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    Ok, so this is NOT an AC problem, but more a HVAC problem.

    By this I mean, you are experiencing problems with the delivery of cool air. So that means the AC system at its base is working. But your controls are not following what you want them to do. That is good news.

    This is most likely a door actuator problem or a AC control panel problem.

    An easy and funny way to check for actuator calibration is to remove the HVAC/ECAS fuse for 10 seconds key off, reinstall the fuse and start the engine, then wait 40 seconds for the HVAC system to re-calibrate itself.

    However, this can only be done if no DTC's are present.

    So your first step before doing the above calibration self test is to make sure there are no HVAC codes present.

    To do that, you will need to scan the system. Do you have any way of doing that on your own?
     
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  3. nickb2

    nickb2 Wrench. I help when I can

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    Paying a good known shop may/probably will cost less than 130$ just to pull the codes of the HVAC system. The HVAC system is very sophisticated on these cars and they will code a specific code for each and every blend,temp door actuator that is malfunctioning.

    Pay a shop to interrogate the system, go no further, and post back once you get the specific code. There is a 90% chance there is one. We will go further from there at this point and save you money cuz that is what we do.
     
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  4. nickb2

    nickb2 Wrench. I help when I can

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    Just by the nature of your initial question, I highly doubt you know someone who has a bi-directional scanner that is capable of getting body codes. So keep that in mind when you think you are getting ripped off because someone has to scan your car with high end equipment. That stuff does not pay for itself and some initial investment on your part is needed to go further.

    Hope you understand how complex this can get. But I assure you, the basic system in your truck is fine. You just have a most likely faulty door actuator, or just in need of a re-calibration. These are not things you can do in your drive way unless you want to follow this chart to the tee and by some magic have a high end scanner lying around.

    Good luck without a scanner that has HVAC capability. So see ACE 3 pdf and take time to read how important it is to get those codes. If not, this thread can get out of hand quickly if proper procedure is not followed. A mode door actuator is cheap, takes about 1 hr to replace, plus the re-calibration.

    If for some reason you choose to replace the mode door actuator, plz do the above re-calibration and all might be well. But if it is a control panel issue, you are looking at more fees in regards to reprogramming the unit via SPS satellite. and if you choose to go scrap yard, well that is just hit and miss.
     

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    Last edited: Jul 17, 2017
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  5. nickb2

    nickb2 Wrench. I help when I can

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    In your case, the HVAC module has deactivated the mode door for the windshield to floor mode because it is at fault. The module sees this as a differential on voltage present as compared to what it wants it to be. Either indicating something is sticking, or the actuator itself is short or open.

    So, again, me being the a hole I am, if you want to save money, you will be most served by reading that PDF to inform yourself. That way, you will prevent yourself from further frustration just because you don't understand the logic behind how the system auto-diagnostics itself. But for that, you need to ask it if it has a code present. (which it most assuredly has).
     
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  6. Cristino Cabrera

    Cristino Cabrera Newbie

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    Nickb2 thanks for your prompt response! I think I will try to do the actuator re-calibration first then from there I will let you know about the results. Greatly appreciately all the help sir.
     
  7. nickb2

    nickb2 Wrench. I help when I can

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    I don't think you understood my initial thought. If the actuator is in a active fault, the re-calibration will not work. But plz feel free to try.

    If for some reason it works, I will be very happy.
     
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  8. Cristino Cabrera

    Cristino Cabrera Newbie

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    I think I did misunderstood what what you were saying given how much technical knowledge I got about HVAC and Auto AC systems. I now have a clearer picture and direction with the information you've given me. I will try to search our area for someone or some shop with a HVAC scanner and go from there. Thanks again and I will keep you posted as soon as I can.
     
  9. Cristino Cabrera

    Cristino Cabrera Newbie

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    nickb2, I just wanted to give you some updates. I have scheduled for an appointment for a diagnose with a reputable auto shop around town but that's til late part of next week. Anyhow, I was kind of really bored today and I decided to do some trouble shooting of my own and found out that the actuator located to the right side of the accelerator pedal seems to actually work normal except that half way through the process (when ac is on and switch to recirc) it snaps or clicks very hard. I wanted to disassemble it to verify what was preventing it from operating smoothly and what was causing it to snap. I somehow pulled back from disassembling it due to that it was already getting too late in the evening. Can you tell me if something might be stuck inside the air duct or something could be broken?
     
  10. kev2

    kev2 wrench

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    STEP BY STEP what nick was suggesting....
    It all depends on codes - if present or not, as mentioned they are B series and not the everyday scanner.
     

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  11. kev2

    kev2 wrench

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    Is this what you are looking at #5
     

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  12. Cristino Cabrera

    Cristino Cabrera Newbie

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    I think it is exactly similar to my truck's AC/HVAC system. I'm pretty sure that it was the actuator mode marked #10 that I noticed actually popping after halfway through the process while switching to defog. Earlier I know that I said that it was clicking or snapping but what I really meant was that it actually pops. I also wanted to verify on the white colored gear which is located right above the said actuator to see if it was broken or off track but I wasn't able to. Thanks!
     
    Last edited: Jul 26, 2017
  13. kev2

    kev2 wrench

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    yes #10 I have no idea why I said #5 .... #10 is mode actuator... Let see what I have for close up diagrams.

    Did you remove fuse for reacal? any luck?
     
  14. Cristino Cabrera

    Cristino Cabrera Newbie

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    Yes, I tried to do a recal twice and to no avail. First, I tried removing all the AC/HVAC fuses and disconnecting the negative battery terminal for 30 seconds and Second, I did what the dealer calls a Global reset which I had to disconnect both the positive and negative battery terminals and making them touch for at least 30 seconds before connecting both terminals back to the battery.
     
  15. kev2

    kev2 wrench

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    look at this video it MAY show a fix - let us know. Sorry not the best but you will have references to your vehicle

     

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