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Chevy Silverado and GMC Sierra Climate Control



  • obyoneobyone Posts: 8,065
    Have you checked the actual radiator or just looking at the overflow tank? If not filled correctly, you could show a full tank while the radiator is less than full. Just a thought. Oh and if you do check the radiator please make sure the truck is cool before doing so.
  • Does anyone know where all the HVAC acutators are? I think I've id'ed the driver's side temp door actuator (above the hump); the px side (on top of duct just below dash; and the mode actuator (driver's side, above right knee & towards center). Is there a 4th actuator, for recirc/fresh air door? is there some sort of 'master actuator', ie, is there a temp door 'upstream' from the driver's side and px temp doors? Also, replaced thermostat, nice hot air for a couple of days only.

    Thanks, Wick
  • ok so I figured a few things out. I was wrong when I said that I am not low on fluid. I was. Am I supposed to fill the radiator up to the fill line in the overflow tank? If so, the dealer put a gallon in and I put a gallon in and it is still not showing in the overflow tank. It blows hot now though which I am thrilled about. There are ZERO signs of leaks, nothing in my driveway and the dealer last week pressure tested it and it was good.

    thanks to all for the help.
  • obyoneobyone Posts: 8,065
    The problem is that the filler hose needs to be primed similar to siphoning. It needs to be filled with coolant so when the radiator overflows, it will flow into the overflow tank.

    How I used to do it was to fill the radiator till the brim, start the truck and wait for the coolant to drop and start to circulate (thermostat open). I then top it off again and notice it will slowly start to overflow. At that point I capped the radiator. It will usually flow enough coolant to push into the overflow tank. You should have some coolant in the recovery tank to make it easier to prime the overflow hose. Gee I hope this makes some sense. My explanation that is.... ;)

    Glad your heater works.
  • I have a 2004 GMC Sierra that has this problem, I am NOT going to pay that kind of money to have it fixed. Have you found the fix for this? Does anyone out there know the answer, it seems this is a fairly common problem but no real answers yet. HELP!! :cry:
  • I have dual temp controls on my 04 silverado. The drivers side only blows only cold air now. I replaced the temp control, but that was not the problem. Any ideas?
  • I hope someone can help, I live in Florida and the heat blowing out whenever the truck's moving is terrible.
  • jimorjimor Posts: 1
    Have a 2003 GMC 1500 and the heater is not hot enough. I've changed the thermostat twice, flushed cooling system, topped off fluids. It circulates through hose. Heater hoses are warm but not hot. Clutch fan disengaged. Heat temperature is between 100 & 105 degrees. Don't know what else to check. Thanks!
  • My 1996 1500 Silverado's heater blower and radio most of the time will not start when switched on. After driving for some time they may activate. They usually come on together but the radio will fade out but the heater continues to operate. After turning engine off the whole process starts all over again. The problem is similar but they donot correlate together. Thought it might be a common ground but have no idea what to do. Thanks
  • dmoshdmosh Posts: 3
    You may have a leak only when the temperature is between cold and hot - watch what happens as the vehicle is warming up. Had on like this once -
  • dmoshdmosh Posts: 3
    After driving in snow my heater blower does not work the next morning.
    It appears to thaw out from engine heat after several hours - not really sure.
    Drove briefly this morning in snow - now blower does not work again.
    Anybody else experienced this.

    Blows snow when on defrost too!! Not good
  • My dealer fixed my draft on the passenger side by resealing the cold air intake for the heater. I beleive they removed the windsheild cowl cover and wiper arms to get at it. I could not see that they did anything inside the cab. It only cost me $112. Hope this helps.
  • c64usc64us Posts: 1
    My problem is a little different from those posted here. I have 2002 2500HD LT, Duramax, with climate control. My AC will work great when it is hot out, but when is is cold, and the windows are fogged up, I cannot get the AC to come on. When I push the AC button it will blink a couple of times then shut off. I would like the AC to come on to help with de-fog. Any suggestions?
  • jborgojborgo Posts: 1
    I was having the same problem with my 2004 2500 Silverado and the dealer replaced the controller along with a modulating valve. I was told the controller was not sending the signal to the valve. Then after the controller was sending the signal the valve was not responding. This is working normal however I have an interment problem sometimes un-commanded hot or cold air starts coming from one side vents only. Going back to the dealer next week.
  • Thanks for the info. I knew something had to be leaking somewhere, and I couldn't find it just looking under the hood or in the cab. It might just be worth a $100 bucks or so to have the dealer take it apart.

    What gets me is, there seems to be a lot of people with this particular problem. But if you take it to a dealer, they act like they've never heard of it! Thanks again for your help.
  • A plastic or some type of composite sleeve has broken on end of the heater core where the hose connects.

    I have been unable to find out from dealers or part stores whether or not this piece is actually a part of the heater core or if this is something that can be purchased separately. Actually I haven't found anyone yet that is familiar with this piece.

    Would you happen to know what this is called,? and whether it can be purchased separately or if it is actually a part of the heater core?
  • obyoneobyone Posts: 8,065
    Are you writing about an off white cylindrical shaped clip that depresses to release the hose from the heater core?

    If so it is sold seperately from the heater core.
  • ZULALA, I have the same problem in a 2001 -- did you find out what was causing the problem. I would surely appreciate help if you found any.

    If I ever turn dial to the hot side - It stays hot "full hot" and will not change... The AC - - everything blows Hot only regardless what I try.
  • I just wanted to ask if you found an answer to the all hot or nothing you described here.... I have a 2001 that does the same thing.... If you turn the "hot" control - that is all you get - and you can't turn it off. It has done the same, in that, I have shut it down and everything work when I started it up a few minutes later... I have not seen or heard anyone that actually figured out the problem - and surely would appreciate learning what and how to fix it -- if anyone knows.

  • Good News! I have a 2001 and finally got this one figured out with the help of my local mechanic.(the dealership never could diagnose the problem) The operation of the lower actuator that opens and closes the the blend door was intermittent.When it would stop in an open position the heat from the heater core would continue to pour in and make it unbearable. Shutting off your vehicle would resetw the actuator to it's home position. This also explains why my AC wasn't always cooling efficiently during the summer months. The actuator costs about $65. To access the actuator remove the air box cover underneath the dash and it is located just to the right of the console. Piece of cake! Hope this helps.
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