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Chevy Silverado and GMC Sierra Climate Control



  • This is a common problem on Chevy and GMC 2000 and on model years. Flushing the entire cooling system will not get to the "Core" of the problem. Try removing the heater hoses and backflush your heater core with a garden hose. Unless it's completely plugged up, which it doesn't sound like, the pressure from the garden hose should be enough to clean it out take care of your problem.
  • Hi.. I see you got your heat prob. handled on the 2001; does your truck have the auto or manual climate control? Dual side climate control? I have poor, intermittent heat, but is very confusing, with auto and dual climate controls on my 2003.

    thx, 24wick
  • My 2001 is a manual knob for single climate control.
  • My 2001 Silverado 1500 leeks cold air on right side of vehicle. I live in a cold climate and the leaking air is unbearable for a passenger. What can I do? Has anyone had the problem?
  • dmoshdmosh Posts: 3
    My 2007 does the same thing - if you need defogging the AC is designed not to work. Need air or heat.

    It is probably logical. Cold air from the AC will condense moisture in saturated air causing more fogging.
  • Message # 95 of 109 diagnoses this problem you identified with the cold air on the passenger side.
  • The AC should work in hot or cold weather with the setting on heat or cool. The one thing the AC will not allow is for the air to be on recirculating instead of fresh air when the selector is on Defrost. Just for the purpose of not putting moisture already in the car up to the window where it might condense. I use the AC all the time in the winter, on Hot and Defrost, to clear the window when the is alot of moisture in the car from the snow on the floor mats, the kids clothes and general perspiration. Good luck.
  • The AC should work in hot or cold weather with the setting on heat or cool. The one thing the AC will not allow is for the air to be on recirculating instead of fresh air when the selector is on Defrost. Just for the purpose of not putting moisture already in the car up to the window where it might condense. I use the AC all the time in the winter, on Hot and Defrost, to clear the window when the is alot of moisture in the car from the snow on the floor mats, the kids clothes and general perspiration. Good luck.
  • I have a 2001 gmc sierra i was told to change the control panel it is all one piece it control's the heat and cold , i also have the same problem, when i turn on heat later i try the ac and it did'nt work ,it worked a few times now it don't turn on at all, it show's the ac is on but it does not work
  • cam988cam988 Posts: 2
    2000 silv. z71--my heat control locks up in the hot position if turned past the mid way point on the blend knob--#2 fan sounds as if blowing fine in all 5 positions,but little to no airflow coming out of vents, was wondering if my vehic. may have filters and if so if they could be glogged up restricting the airflow?--#3 i am also having the cold feet problem on passenger side tired of hearing my wife complain--lol, would appreciate any help, and if filters might be prob. would appreciate a discription of where they are and how to get to them. thanks
  • obyoneobyone Posts: 8,054
    The filters are located directly above your wife's feet. Assuming you've never changed them They are probably clogged and hopefully not mold infected.

    You can probably get a new controller on ebay. To change it takes about 10 minutes. You can get the a/c filters on ebay also and those take about 10 minutes to change too.
  • Thanks so much for the information. And thank your mechanic for me as well. Does anyone know why the dealers have no clue about this problem? Thanks again. Ed
  • serickserick Posts: 2
    My local dealer fixed cold air leek. They told me that the gasket between the heater and the fire wall is inadequate. The removed the gasket and sealed with silicone. This has fixed the problem.
  • I have a 2000 silverado that blows cold air
    intermitently while the heat is on. I've replaced
    the thermostat and flushed out the heater core,
    no apparent blockage. Anyone have any ideas
    where I should look next ?
  • cam988cam988 Posts: 2
    thinks for the help---i am an ase certified mechanic but had never heard of the heppa filters in the ac,also good on the actuator, i guess i will have to find a schematic for the heater seal, thanks for all the help.
  • Where the heck would i be looking for the low side on the AC system so I can add R-34? My AC will not kick on and I am pretty sure I'm low on freon.
  • obyoneobyone Posts: 8,054
    That would be the valve closest to the firewall.
  • Thanks. I saw two valves there but they somehow did not look right to me. I put my gauge on the one farthest out. So, as I'm thinking about it, I dont know what else the other one would be for except for the recharge valve. Thanks again.
  • canam2canam2 Posts: 3
    My a/c only blows cold air on the passenger side, and constantly blows hot air on drives side. I am assuming it is the blend door actuator. Is there a way to physicaly see if it is not working? Or am I just going to have to replace it. Also how likely is it that there could be something wrong with the blend door iteself or something lodged in there? Also as I was digging around I noticed my HVAC assembly (big black box) is cracked behind the glove box, Would this be causing my problems?
  • obyoneobyone Posts: 8,054
    When you say "hot" do you mean heated air? or uncooled air from the exterior of the vehicle?
  • ranvonsranvons Posts: 4
    My blower switch/knob only operates at #5 now, they have been steadily going out one by one. The dealer wants to replace the entire relay module at $150. Is there a simpler less costly fix for this problem?

    Thanks, Randy
  • obyoneobyone Posts: 8,054
    Each setting is controlled by a diode. You can replace all 5 diodes for $10.
  • ranvonsranvons Posts: 4
    THANKS! But where the heck would I find the diodes, unless I am looking for the wrong thing, I cannot find it anywhere...HELP

  • obyoneobyone Posts: 8,054
    The are located on the backside of the controller. It requires that you remove the controller from the dash to work on. I'm surprised that the dealer didn't mention it as it is a common item that stops working every couple of years and for them is very easy to do. Not much profit though.
  • canam2canam2 Posts: 3
    The air that comes out is heated.
  • obyoneobyone Posts: 8,054
    See post #117
  • jacedjaced Posts: 1
    Im experiencing a problem with my a/c compressor. It's never engaging when I hit the button to turn it on. I stopped at a car shop yesterday and they told me it's charged with freon and that they think it is an electrical problem. Well since im an electrician not a mechanic I figured i might be able to trouble-shoot the problem. All fuses seemed to be ok by sight and checked good with my meter. The larger relay in the electrical box had continuity between two diagonal poles. Sorry for the length of the question, just trying to be informative. Thanks a lot, and I forgot to tell you it's a 2000 model chevrolet 1500 5.3 liter V8.
  • snowbugcasnowbugca Posts: 5
    You already got the diagnosis right. I just had mine changed. Cost about $560. (not at a dealer) the part is $210. I beleive it is the farthest left one. There is 3 or 4 of these motors on the HVAC. I don`t think the crack is the problem. Jim
  • canam2canam2 Posts: 3
    I have dual climate control and it has been blowing heated air out of the drivers side for some time now. I removed the blend door actuator that controls the drivers side. It appears there is a plasitc shaft that goes from the actuator to the "HVAC Box". This shaft is sheared off flush with the actuator. What is my next course of action? Can the broken piece be removed without tearing the dash apart? Im afraid there must be something blocking the blend door, that made is shear off in the first place. What kind of job is is to get at something like that?
    Thank you.
  • cfi62cfi62 Posts: 1
    I too have a similar problem. this is on a 2004 Sierra with dual climate controls. the blow is the only thing that responds to any controls. the ac button will not turn green when pushed. the dampers do not modulate when moved to another position and nothing but hot air is coming out the vents. also, the recirculate button light will not come on to indicate which mode it is in. any help would be thankful. I checked the fuses (ones that seemed involved with the ac and control) visually and all appeared ok. thanks in advance. chuck
  • maynor007maynor007 Posts: 2
    I have the same problem with my 2007 Avalanche LTZ. The drivers side AC works fine. The passenger side will start to blow heat after running for awhile. When the truck is shut off, the restarted, it will blow correctly. Then it will go back to blowing heated air on the passengers side, while the drivers side is blowing cold air. Dealer wants to take apart the dash to find the problem.
  • Hey all,
    Hope someone out there can help. Basically the Trucks AC was working fine and then the other day only blowing warm air. Ran the truck on a 20 minute trip with the AC on as I've heard it can take a bit to come on and still nothing but warm air. Check the refrigerant and it was fine. When turning on the AC you can hear/feel the power transfer as the motor send power. Took a look at the compressor and it was not turning when the AC was switched on. Got my hand down there and was able to move it so I know it's not seized up. Checked fuses in the cabin and under the hood that were related to the AC and all were good. Anybody have any idea what could be causing this? I'd like to fix it myself as I enjoy that sort of thing also would like to avid dealer pricing where ever possible. Thanks in advance....
  • obyoneobyone Posts: 8,054
    There is only one reason for it blowing warm air and that's insufficient amount of R134a. You stated that you checked the refrigerant. Exactly how did you do this?
  • tracyh68tracyh68 Posts: 5
    The dealer told me that the actuator needing replaced is causing the air to blow warm on the drivers side and cold on the passenger side.
  • wstarneswstarnes Posts: 5
    Low refrigerate is never the root cause of a cooling problem, just a symptom of a another problem somewhere else in the system.Chevy P/U's are notorious for actuator blend door problems which can affect the ability to control the air or heat depending on where it got stuck or quit working..
  • my 95 pickup air control has 5 speeds they one by one went out til finally all have quit working, I have tested the blower motor and it works ..what is my problem and how do I fix I need to replace the whole climate control board..someone commented about a diode..what is that and where do u find it.
  • 2004 Silverado 1500
    My air conditioning will not turn off. If I turn the dual climate up to full heat and kick air flow to the defroster, I can temporarily shut off AC, but the minute I turn back to just letting air flow through, the AC kicks back on. My re-circ works fine, however. Is it a short in the electrical system?
  • tthoresotthoreso Posts: 3
    I'm looking for clarification of operation of the Automatic climate control as mine doesn't operate the same as my other car which is not a GM.

    When it is hot outside and very hot inside the cab, when I start my truck the fan goes up to 4 bars and stays there. If I turn the temp up a deg then back to the original temperature the fans goes full speed. But never reaches full speed if I don't adjust the temperature.

    My other car (Acura), same conditions, when you start the car it switchs to recirculated air and puts the fan full blast, then when it cools down inside the fan slows down and flips back to fresh air. To me this is how it should work.

    Can anyone else let me know if your works like my truck or the car?
  • seafarmerseafarmer Posts: 16
    Diodes are generally small & cylinder shaped with lead wires coming out the ends (axial leaded). They are directional allowing current flow in only one direction so be certain to install it correctly. You can check the old one with a multi-meter. You will get no reading one way, swithc the multi-meter probes and you'll get a reading. Check out under key word diode, discrete semiconductor for a great selection or Radio Shack carries a few common ones. They generally are identified as a 1N#### (i.e. 1N4001) if you can pull it off the old component.
  • tsh1282tsh1282 Posts: 3
    I had to jump start my truck a few months ago and ever since then the ac will only blow through the defrost. I have called the dealership and they told me that that is a common problem and that something had to be reset. Unfortunatley they could not tell me how to do it myself. When I first start the truck the air will breifly blow through the defrost and then it will blow through the vents for a few second and then it reverts back to the defrost. Can anyone help me please? Oh, it is the dual climate control and it is not the digital contols, it is the manual.
  • obyoneobyone Posts: 8,054
    Disconnect the battery for ten minutes and reconnect.
  • tsh1282tsh1282 Posts: 3
    I have tired that and I have also pulled the fuse for ten seconds and turned the truck on for forty seconds then started the truck. None of these things fixed the problem. The only thing that I can figure is that it might be the ac controls themselves because I can actually hear the doors open when I first start the truck and then they close back. Thanks
  • tmpantanotmpantano Posts: 1
    Hello Everyone!
    I have a 95 Chevy Tahoe and I am having problems with the heat. When I'm on the freeway or going up hill, HOT (It melted a fleece blanket that I placed down there) air is comming fron the center floor vent. I took it to the delaer and he said that there was an actuator that needed replacing. And of course that work could have been done for $620.00 and I just couldn't justify that kind of money for a $50.oo dollar part.
    I took it home and I took the cover off of the center duct. As I was driving you can feel that door open when I go up hill or drive on the freeway. Even if I tun the dial on the dash to defrost or any other setting, HOT air still comes out of the floor vent. I should also mention that the A/C is not working and when the dial is set to the cool position, warm air is still comming out of the vents.
    Any help would be greatly appreciated!!!!
  • tsh1282tsh1282 Posts: 3
    This is an update on what I have done. I have recently removed the computer and had it reflashed but this did not solve my problem. I have a theory and I wanted an opinion before I do this. I believe that the battery is the original one, which would make it 5 years old. It has enough power to start the truck but I was wandering if it did not have the proper amperage, could it effect the ac controls to where they are trying to recalibrate everytime I start the truck?
  • obyoneobyone Posts: 8,054
    Since the battery is 5 years old I'd replace it. That is not saying that it is the cause of the problem with the AC. If it has enough juice to start the truck I'd assume it has enough to retain the memory. If that wasn't the case there would be other gremlins showing up.
  • swamperswamper Posts: 1
    The a/c blower in my truck will not come on, the selector for vents and defrost will not change either. The compressor is working, I could not find any blown fuses. The lights on the control panel went off then came back on, the next day the blower would not come on. The truck is out of warranty, any ideas on what else to check? Could the control panel have shorted out without blowing a fuse?
  • obyoneobyone Posts: 8,054
    The blower speed is controlled by independent diodes. However, I've never heard of all of them failing at once. If all the fuses are good there is a chance that the controller itself has failed.
  • wtpearsonwtpearson Posts: 1
    Blower Resistor at Napa $25.00, same Echlin part as at the dealer. Of course the female connector was melted along with the terminal. Harness is $95.00 at dealer. Found online that a 7 wire pigtail female connector with sleeves is the new alternative for the entire wiring harness. Found online at +Harnesses&catID=61&subcatname=G%2EM%2E+Electrical+Repair+Harnesses" as a new option compatible with GM part #15862656, ACDelco PT2195. Cost #14.62 plus shipping.
  • ia2189ia2189 Posts: 2
    "When it is hot outside and very hot inside the cab, when I start my truck the fan goes up to 4 bars and stays there. If I turn the temp up a deg then back to the original temperature the fans goes full speed. But never reaches full speed if I don't adjust the temperature."

    Anybody come up with an answer for this? My 2005 1500 is doing the exact same thing. Already had it in once but replacing right and left actuators does not appear to have worked. Any ideas are greatly appreciated!!!
  • dansyotadansyota Posts: 2
    I think i can help you i had this very same problem after i drained my battery. I saw a television show were they had to reset the computer on a new cummins so i thought i'd try it on my chevy (2004 z71). all you need to do is diconnect both battery terminals and hold them together for about 30-45 seconds i don't know why it works but it did on my truck. As soon as i hooked my battery back up I started the truck and let it run for a minute and all the controls worked fine not just on defrost. I hope this helps you out.
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