1984 GMC C3500 Weak heat in 1984 GMC truck

1984 GMC C3500
98,777 MILES • V8 • 4WD • AUTOMATIC
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WIL454
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I have weak heat in a 84 GMC. I have replaced the heater core and thermostat, the supply hose from the core is hot, the return hose from the core in warm. I adjusted the cable to the air mixing door. After all that it still blows on average 100 degree air. The truck comes up to temp 185 and is stable. If anyone has any ideas let me know
Dec 7, 2009 at 6:48 PM
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JACOBANDNICKOLAS
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What temp thermostat did you install? THe factory one is 195. THerefore, the engine should be running at that or higher. Also, have you tried to flush the heater core?
Dec 7, 2009 at 11:09 PM
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WIL454
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New core new stat
Dec 8, 2009 at 2:20 PM
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JACOBANDNICKOLAS
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Do you remember if it was a 195 degree stat?
Dec 16, 2009 at 8:45 PM