2000 Blazer No Heat

http://Blazer.autoboardz.com/2000-chevy-blazer-heater-heat-ftopict249317.html (2000 chevy blazer heater (no heat))
I tried to get heat today and it just has a fiant bit of heat. All the vents blow where they should.but the temp control in the center of the dash doesn't seem to to be letting the hot water in. T..
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http://Blazer.autoboardz.com/2000-Blazer-Heat-Blows-Cool-Air-Help-Headed-Nort-ftopict249414.html (2000 Blazer - No Heat -Blows Cool Air ... Help Headed Nort..)
Everything including the AC, blower, vents seem to work fine. I replaced the thermostat thinking that was it and oh well .... no heat. I notice that the vehicle doesn't reach the normal running temp..
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