Heater not blowing where needed

[spettit379]

Hey Guys
I have an 04 Ex with a 6.0 and Electronic climate control. It blows out the defrosters only. It was cycling between floor, then vents, and defroster. Now it's only on defroster no matter what position I select. Is there a vacuum pump of some sort on this engine? Any help would be appreciated. Thanks

[GregsSD]

The climate control system will revert to defrost if there is a problem with the vacuum.

So you either have a vacuum leak, or your vacuum pump is bad.

The vacuum pump is under the hood on the passenger side fender, when you first start your truck you should hear the pump run for a short time, if it keeps on running then you have a vacuum leak.

[spettit379]

Yep. It was a vacuum leak. Oddly enough when I switched my transfer case from 2wd to 4wd and back again the leak stopped and the heat started working fine.

[Karls03]

Check the vacuum lines from your frame to the axle, the vacuum hubs blow air through the defroster when they have a leak. Hence cycling the transfer case switch results.