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Chevy Silverado and GMC Sierra Climate Control



  • Hi Fritch, your problem sounds just like many. I had a problem such that the only real complaint I had was that the a/c wouldn't get as cold as it should. The a/c unit was working just fine, the air mixing valves wouldn't let it go to full cold. I tried to unhook the neg. post of the battery to try to "reboot' the computer and it did nothing the first couple of times. Then one time I tried it the system would only blow high out of the defrost. After reading all the posts I could find, I decided to see if the stealership could fix it. They said the computer would have to be reset using their expensive time and equipment. They tried to reset it and it would cool great! Only thing is, they said that now it would only blow at the high setting no matter what they did. They wanted hundreds to "fix" it and I said no. I went out to go home and it worked perfectly and has ever since.

    So - I think it depends on the stealership and whether they know how to use their equipment whether or not they can fix these problems. I think I was lucky because it only cost me around $100.
  • Did you ever find out what the problem was? I have a 2002 Chevy Silverado extended cab with the same problem. Any help would be appreciated.
  • dykesdykes Posts: 1
    i have the same issue have you had any leads on how to fix this problem??
  • 3chvytrks3chvytrks Posts: 2
    edited February 2010
    Hello wakejunkie. Did you have any luck finding a solution to your problem? (only getting heat at full 90 degree setting) I have an 03' Suburban Z71 and a 03' K2500 HD with the EXACT same problem on both vehicles. Seems common, someone must have the answer. I have disconnected the neg cable from the batt for a few min, then left the key on without starting for a few min after reconnecting the cable. No luck. I have read a few other post saying to leave the neg cable disconnected for 10 min or to disconnect both cables and hold them together. Plan on trying both, in addition to removing HVAC fuse. Removing the DIC (Driver information center) fuse has worked on the gauge (stepper motor) problems on the 2500.
  • I have the same problem with my truck. I had the battery disconnected when I was replacing stereo speakers and after that no heat when auto climate is set below 90 degrees. Can anyone help? :( :( :( :(
  • 3chvytrks3chvytrks Posts: 2
    edited February 2010
    If this happend after the batt. was disconnected, then that leads me to believe that it might be a reset issue. I still have yet to try some of the tricks I have read about on reseting the climate control (computer). I have read some more on the problem and talked with some experts...and their best guess was an interior temp. control sensor, or a bad climate control system. My plan is to try all the reset tricks, then replace the sensor (depending on cost). I am sure it is to expensive of a fix to replace the whole system.
  • cliff85jcliff85j Posts: 7
  • cliff85jcliff85j Posts: 7
    the air recirc on my 05 silverado stopped working. when i push the button it flashes a few times goes out and it doesn't work. any ideas?
  • Mine was doing the same thing. Yesterday it stopped working altogether. I checked the fuse, bu it was good. Did you figure out what was causing the problem on your truck?
  • foxwoodfoxwood Posts: 1
    I have a 1999 Sierra and it has been attacked by pack rats (the real rats). The chewed out the rubber flaps that were located inside the fender just forward of the door. The have carried acorns into the ductwork. I pulled the plastic screening off of the air intake just below the windshield and used my shop vac but wasn't able to vac anything out. I removed the cabin air filter elements and pieces of acorns and rat dropping came out. Does anyone have any ideas how to block off the area where the rubber flaps were and what is between the outside air intake and the cabin air filter. There is still something blocking the air when I turn the blower up to 3 or more.
  • when my truck is warm and the controller has not been on cold the whole time it blows hot. only in summer. if knob is moved to warm in mornings, ac blows warm as soon as truck is started. any help would be appreciated. thanks in advance!!
  • duncanm2duncanm2 Posts: 2
    My 2004 Sierra fan switch was erratic then failed completely, fuse was ok. I removed the heater control panel and the back of the switch was melted. The fan was ok but seemed to be slightly stiff when spun by hand, so I replaced the motor and the fan control switch and everything is fine. My 91 GMC had a dashboard fire caused by a melted connector in the heater fan circuit. Why can't GM build a heater control that won't meltdown? Thicker wire or better fuses? Something other than nuclear meltdown of controls or resistor boards?
  • greg94greg94 Posts: 4
    same with our 2006 sierra.....
  • robinhood8robinhood8 Posts: 2
  • robinhood8robinhood8 Posts: 2
    If you have a Bumping noise around the heater blower, like I did ,then maybe this will help you.
    My bumping noise occured when you turned on the ignition to start or auxillary and also when you turned off the ignition. It would last for maybe 30 seconds or so. Now, I have seen people asking for instructions about how to remove the dash and all the work that that involves.

    OK here was my solution:
    By looking and feeling under the dash at the heater I could pretty much feel where the noise was coming from. It was right at a little vent door under the heater. (maybe, it is called a blend door) Anyway I found that when It was making this bumping noise that if I pushed up on the door on the unhinged side the noise stopped. So I thought, why not try to just block it open with something and see if that would stop the bumping. I had a little length of about 1/2 in. gas line left from another project. I cut off a piece about an inch & a half long and wedged it in between the door and where it seated itself. WaLa, no more noise.
    I don't guarantee it will work for your problem but it worked for me, and so far everthing seems to work perfectly normal with the heater. So it saved me pulling the dash as suggested by many blogs that I have read in either work or the cost to take it to a shop. If you have the same problem maybe it will work for you. If it works you can send me the $600. or so that people have said it costs to fix. I"m kidding. To tell you the truth it took longer to write this blog than to fix the problem.

    disclaimer: I don't guarantee that it doesn't cause a problem but I havn't had any problem myself.
  • damatt18damatt18 Posts: 1
    I have a 2005 Chevy Silverado 1500v6. Imagine the climate control dash set all the way down to cool and a rapid popping noise occurring. The noise is similar to gulping a drink very rapidly. The sound occurrs whether the air conditioning is on or off, or no matter if the blower is off or on high. What is this and how to fix it??????
  • mine does that only on certain level settings. If I recirculate inside air the level area can only work with say, the mid level or floor level. Some combos don't work. You may know this but just wanted to offer some help in case.
  • charlie107charlie107 Posts: 1
    edited June 2010
    Temperature control not working. Hot air constantly coming into cab--cannot shut off--. even though the controls are shut off or put in air condition mode. I tried overriding the blend door acuator switch and manually moving the flap with the truck running, but the heater core under dash still stayed hot. Is there some type of switch out on the firewall that prevents the hot water coming into the cab to the heater core; or could it simply be the control temp. switches on the control panel? Does anyone have a solution? Thanks.
  • clovelesscloveless Posts: 5
    As a last resort to be able to survive the heat for a while, I put a valve in the hot line from the radiator to the heater coil. It's on the right side of the engine and you can see it going into the heater coil. I bought one from a local parts house. Shut if off and it insures no heat reaches the heater coil.
  • dowelldrdowelldr Posts: 1
    This is a year late, but I have the same problem with my 1997 Silverado. I just spoke with my mechanic and I like his explanation. He says that the problem is caused by slightly low freon or possibly running the system on Max A/C for too long. The issue occurs when the core freezes up, or water ices over the ports preventing the cooled air from escaping into the vents from the core. When you turn the A/C off, the core has time to warm up, so the ice melts and the problem disappears...until you turn the A?C back on and it freezes over again. I'm not sure how low freon contributes to this, but his theory sounds plausible to me. To prevent the core from freezing, try not using Max A/C after the truck has run for a bit. Also, try turning the temperature to a warmer (less cool) setting to prevent the icing in the first place. I haven't tried this yet, but I'm hoping it will fix the problem until I can get my truck to the shop to check the freon levels.
  • stretch87stretch87 Posts: 2
    edited June 2010
    Hqave 2000 Z-71 extended cab,221,000 miles ! I still love this truck ,runs,rides fantastic still!!!! I Recently replaced battery, & have since had no A/C!! My mechanic & I tested all circuits,fuses,switches. charge.Etc. ALL seems well!!!! Went to dealer to have computer "RELEARN" how to turn on A/C!! They said blah blah blah BS... All worked fine till battery replacement,now ????????? Do not trust dealers to do right thing ,especially since my mechanic is an A+++ !! Also not really looking to drop few hundred $$$$ for &%^#^^% dealer to make-up solution!!! ANY IDEAS???? :mad: :cry: BTW A/C worked fine day of replacement,stopped working after!!
  • 04 Sierra climate fan control works on #2 and up fan speed, but not on 0 or 1, but will work when truck accelerates. Any tips?
  • dbbarretdbbarret Posts: 3
    I have same problem in 2005 GMC Sierra 1500. Used to only work at 2 and up (for a few months) but now it only works at 3 and up!!! Any ideas?
  • obyoneobyone Posts: 8,054
    You can find a replacement controller for cheap on ebay.
  • dbbarretdbbarret Posts: 3
    What exactly is the part called?
  • obyoneobyone Posts: 8,054
    You can find it here:

    Enter year make model
    under hvac---> controls-->dash control unit.

    You will have four selections. To be sure you order the correct one you will need to email them with your vin prior to ordering.

    Or you could have yours rebuilt here:


    I couldn't find any listing for a used replacement unit at this time. You could search ebay for GMC HVAC controller.
  • dbbarretdbbarret Posts: 3
    Thanks for your help - I emailed them with my VIN. Is installation pretty straightforward? plug and play?
  • obyoneobyone Posts: 8,054
    Yes plug and play
  • Got out of the truck yesterday and the vent fan just came on ...keys in hand. Turned off ac and fan but it came back on. any ideas why this is happening.
    Could there be a short somewhere.

    Thanks, steve
  • di you ever find a fix for your ac problems. i just bought an 2004 gmc sierra and its blowing hot out of the driver side, any info would help thanks
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