what would make your heat blow hot when your driving but blow cold when at idle

2002 SATURN SL1
145,000 MILES
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[email protected]
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Ive replaced the water pump,thermostat and over flow cap but still does the same thing at this point I'm lost and don't know what else to look at
Dec 14, 2011 at 4:08 PM
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SATURNTECH9
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Sound like a restricted or clogged up heater core.Have you put any coolant stop leak in the coolant?
Dec 14, 2011 at 4:11 PM
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[email protected]
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No but it is a brown looking color how would I flush the heater core out
Dec 14, 2011 at 4:16 PM
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SATURNTECH9
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I would remove both heater hoses then try flushing water thru it with a hose.If you have a air compressor turn the regulator way down and use a little compressed air to clear it.
Dec 14, 2011 at 4:30 PM
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Both heater hoses go into my firewall right
Dec 14, 2011 at 5:00 PM