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Discussion Starter · #1 ·
Ok guys hopefully someone here can shed a little light on my problem. Heres what I have. I have a 2006 Sierra crew cab with 5.3L, With my truck up to normal operating temperature if I turn my heater on it blows cool air. If I floor the truck and get the RPMs up it will start blowing hot and stay hot for about 1- minutes then it gets cool again and I have to rev the engine again. After the engine rev the heater blows GREAt for the 1-2 minutes that it works. if ANYONE can help me figure this out I will be forever indebted lol
 

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Bunn
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Needs flush. possible stopped up heater core..or propeller on water pump could be stripped. those are the basics to start with:big_banana_Dance:
 

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This place sucks dicks
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How is the coolant level?
 

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Discussion Starter · #4 ·
Sorry it took so long to reply guys, I have been out of town for work. The coolant level is fine and the coolant that is in there has <20,000 miles on it after a flush a while back. If the impeller on the water pump was bad wouldn't the truck try to run hot? I also recently started getting a tighten fuel cap message so I replaced fuel cap and it still comes up. Could the the two problems be related? Like a vacuum leak not allowing the heater open, which sounds logical because the higher rpms create more vacuum making it work when I rev????
 

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Knuckle Buster
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bad heater core...I had the same problem on the denali, but luckily it was just a low coolant level for some reason. not sure that your gas tank cap light indication has anything to do with your heater not running hot unless you are well above idle RPM.
 

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This place sucks dicks
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Sorry it took so long to reply guys, I have been out of town for work. The coolant level is fine and the coolant that is in there has <20,000 miles on it after a flush a while back. If the impeller on the water pump was bad wouldn't the truck try to run hot? I also recently started getting a tighten fuel cap message so I replaced fuel cap and it still comes up. Could the the two problems be related? Like a vacuum leak not allowing the heater open, which sounds logical because the higher rpms create more vacuum making it work when I rev????
No theyre not related.
 

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cunts
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I would have to say heater core going bad. They're not hard to change, just a little time consuming. be sure to have floormats and a container to let it drip.
 
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