sntrym
I'm Awesome
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- Sep 9, 2015
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One other thing to check - Follow the hose from the back of the intake manifold to the heater core. Does it go straight in, or is there a hose assembly that it goes to? If it goes to an assembly, this is the heater core bypass. Using vacuum, it's supposed to open to let coolant flow to the heater core when the A/C is not on. When the A/C is on, it closes and routes the coolant to the radiator to provide colder air. Not all trucks have it, but some do. If the bypass is bad, everything will work fine, but you won't get heat. This happened in my Yukon. I remove the bypass and let coolant flow through the heater core all the time, and I don't have any A/C problems.