2000 Silverado ..... No heat

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  #1  
Old 12-01-12, 05:26 PM
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2000 Silverado ..... No heat

This is my second problem that I need to address. Vehicle is 2000 Silverado LS Extended cab w/ 4.8L

Problem...I am not getting any heat out of the vents even once the truck warms up. I don't know if there are different heater control set ups for this truck or not but mine has 3 control knobs in the center of the dash below the radio.

The knob on the left controls the fan speed. The center control knob contols temp hot to cold. The knob on the right controls which vent the air comes out of such as dash, floor board, defroster, ect...

The fan is working fine and the knob on the right controlling which vent it comes out of seems to be working ok. The problem seems to be that even if I rotate the center temp. control knob all of the way to the right I am not getting hot air from the vent. It stays cool.

I am under the impression that the right and left knob are working vaccuum actuators but I don't know if the temp knob in the middle is vac. operated or electric.

So does anyone have any ideas as to the most likely problem and how I could proceed to check it? Thanks
 
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Old 12-01-12, 06:10 PM
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I'll start with a couple of basic questions.
1) Is the engine getting to normal operation temp according to the gauge? While that sounds silly....
2) Initially when I started reading the post, my mind went to; someone installed a shut off valve in a heater hose under the hood. Is this a truck you have had a while or did you buy this truck used since last winter?
 
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Old 12-01-12, 09:14 PM
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1.) according to the temp gauge on the dash it is getting up to normal temp.

2.) I am the original owner of the truck. I bought it new. It has not had any work done to it and has not been to any shop in the past few years.
 
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Old 12-02-12, 02:45 AM
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Do you know if anyone has ever used Stop Leak in the radiator? I had this problem on a 1993 K1500. It stopped up the heater core and prevented hot water from circulating through it. My solution on that was to back flush the core. Remove the inlet and outlet hoses to the core and apply pressurized water (from a garden hose) into the outlet end. If it is clogged, you will see a bunch of crap exit the inlet hose.
 
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Old 12-03-12, 01:37 AM
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No one has ever added stop leak to the radiator. I guess that there is the possibility that the heater core could be stopped up though. What do you other guys think? The truck has about 188,000 miles on it.
 
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Old 12-03-12, 02:02 AM
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If you want to check for a plugged core issue.......you'll need to go under the hood and find the two hoses to the heater core. They should both be hot after the engine warms up. If they are....then you have a damper issue. If both aren't hot then you may have a plugged core.
 
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Old 12-03-12, 12:48 PM
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sounds like you have a blend door or blend door motor problem. The blend door controls how much of the heat from the heater core is let into the heater plenum and out to your vents.. Sometimes the motors go out and sometimes the door pivots break..
 
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Old 12-03-12, 12:59 PM
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Have you checked the coolant level? Low coolant won't reach the core.
 
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Old 12-03-12, 02:53 PM
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Good point toolmon. Cummins Diesels will run forever on an empty radiator, since they run cool to begin with. I noticed my heat turn to cold the other afternoon when I turned a corner. Bingo. Low fluid. Good possibility.
 
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Old 12-05-12, 05:05 AM
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coolant level is good. I will check the hoses going to and from the core today.
 
  #11  
Old 12-06-12, 03:22 AM
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checked heater hoses and both sides are warm once truck warms up.
 
  #12  
Old 12-06-12, 07:54 AM
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These trucks had trouble with blend door actuators,control levers, and the dash control itself. All the controls are electrical. Wish I could be more specific.
 
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Old 12-09-12, 10:14 AM
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well, if the heater core hoses are same temperature, next question is - do the blender doors operate in any desired position?
as if the hoses are same temp, then coolant circulates through the core. So, it's hot/cold door or hot/cold actuator or hot/cold climate control knob.
I just read though my 99 manual. What it says is to disconnect both heater core hoses and back flush core with water. Which is likely the last call attempt before replacing core, if the rest of the things involved work properly.
I'd say, as it's very easy to do, pull climate control out and check on connector in the back.
You can even go for broke and replace it, they are not expensive at junk yards or ebay
AC/HEATER Climate Control MODULE 1999 2000 2001 2002 CHEVY SILVERADO on eBay!
 
  #14  
Old 12-29-12, 04:25 PM
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Before changing the heater core, do a search for blend door actuator test for your truck. There is a way to test that. I cant remember if its the blend or the vent selector, but one of them requires the removal of pretty much the entire dash. Good luck.
 
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