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Defrost

Old Nov 4, 2010 | 06:18 AM
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plumbfishy
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Defrost

When I have the heat or AC turned on it only blows out the defrost any help? Manual look out hubs.
 
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Old Nov 4, 2010 | 06:32 AM
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I'm guessing you have 4x4.

Common 4x4 problem, vacuum leak in the ESOF system. Check hoses on front hubs.......
 
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Old Nov 4, 2010 | 07:21 AM
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The HVAC blend door is actuated by vacuum and since our engines do not create vacuum by themselves, there is an underhood vacuum pump. Make sure your pump is working and then you will need a vacuum gauge or hand pump to check/test the lines going to the under dash controls to see where you are losing the vacuum.

The most common areas are a bad pump or cracked hose between the pump and firewall.
 
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