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. Their isn't any
control valve in the heater line under the hood. The hoses go from the block straight to the core. Does anyone know what regulates the water flow. It was working good the last time I used it. The rad is full. aepowell .
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You have an system called blend air there are no valves just air doors that direct air through ac evap. or heater core. If these doors are not programmed properly heating or cooling will be compromised.
Rey
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I had the same problem on my 2000 GMC Sierra (v8) and what i did was removed the two hoses that go to the firewall down to the heater core, and placed my garden hose (cut it and clamped it) to the left outlet on the heater core (reverse flush) and clamped about 6 foot of hose to the right inlet, just so that all the water drained away from the motor.....then i cranked the water hose, and flushed out the core! at first the flow of the water was weak, but after a minute or so it flowed strong! unblocking the restriction. let that flow for about ten minutes, then switched the hoses and flushed it in the normal flow direction! now my heat is HOT! just pop the hood after your at normal operating temperture and feel the hose that runs to the inlet (right side - firewall) should be hot, as well as the left side (Outlet) if the left side hose is cool, you may have some heater core blockage!

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