heater and four wheel drive wont go in four hi or low

2000 GMC YUKON
185,000 MILES • 5.3L • V8 • 4WD • AUTOMATIC
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NEO2010
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  • 1 POST
I have a 2000 Yukon SLT and it will blow heat out the back but the front just blows cold air do u think its the thermostat or what I put antifreeze in it because I thought it may be low I just don't know what to do.
I try to use the four wheel drive in hi and low when u push the button the light just flashes on goes right back in 2 wheel dive I have replace the buttons and it still does the same thing.
Jan 6, 2014 at 5:02 PM
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JACOBANDNICKOLAS
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  • 110,175 POSTS
If the engine is not overheating and is warming up to normal operating temp, the thermostat is fine. What I need you to check is this. With the engine warm and the heater on high, feel both heater core hoses to determine if both are hot. If they are, chances are there is a problem with the blend air door. If only one hose is hot and the other isn't, chances are the heater core is plugged and will need flushed.
Jan 6, 2014 at 5:34 PM