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Silverado heater

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by 95silv001, Feb 26, 2014.

  1. 95silv001

    95silv001 New Member

    Hello, I have a 2000 Silverado with a heater problem. When I leave the heat completely off and drive for a while (while at operating temp) and I turn the heat on it's nice and warm for about 10-15 seconds and then goes cool, not super cold but certainly not hot. If I repeat it it does the same thing. I had the heater core flushed some time back and I changed the T-stat. After that the heat worked great. When I feel the heater hoses both seem to be at the same temp. I have not overheated it ever since I have owned it (which is a long time now) I can watch the temp gauge and it seems to come right up to temp no problem. Could the t-stat be bad? where else could the problem be? I am not losing coolant at all, and my blend door seems to move fine (hot/cold).
  2. Pikey

    Pikey Moderator Staff Member 2 Years ROTM Winner 1000 Posts

    your heater core could be plugged again. That would explain why it is hot and then gets cold. Both hoses being hot indicates that fluid is moving thru it. But, the concern now is the rate that the fluid is going thru it. Some guys here have had luck disconnecting both hoses, pouring clr in one of the hoses. Letting it sit for a while and then flushing it thru. I would rule out the t-stat because you said that the engine operating temp has remained normal
    Last edited: Feb 26, 2014
  3. 95silv001

    95silv001 New Member

    Thanks, I will try it and get back to you
  4. silverado002

    silverado002 Member

    Do you have AC? A thought I had is that you could have a heater vent door under the dash not functioning correctly and allowing fresh air or AC air to enter the outlets.
  5. j cat

    j cat Rockstar 3 Years 1000 Posts

    both heater hoses need be hot . if they are not hot then the heater core is plugged again. the reason this may occur several times is because it is nearly impossible to completely drain the block and flush out the engines coolant system. the block has 2 plugs on each side. these are locktighted in my 5.3L engine. and the dealership techs said do not screw with them. these plugs are where the block heaters would go.

    best to drain the radiator. then remove the heater hoses at the engine [NOT THE FIREWALL]Then you place one hose in a bucket and using a water hose flush out the heater.. then you do the reverse and continue until the bucket flow is now clean with no debris..then I use some air pressure and this removes the water and any other material stuck in the core.

    this vehicle will produce more heat than you can stand it will burn your toes..

    2000 silv 5.3L 4X4 original owner.

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