I have a 2005 2500 express, the AC works fine but when I turn the temp all the way up and switch off AC I do not get any heat. the motor runs at 190-200 range. where is the control to turn on the hot water to the heater.
I have to travel from FL to NJ and it is 15 degrees up there right now
HELP

 

is the temp blend door moving when you move the temp setting from cold to hot? If its not, check the vacuum connections to the vacuum actuators. there is a vacuum line in the passenger footwell that always get kicked off.

 

You can also check to see if both heater hose going to the heater are equally hot. If one is much hotter than the other then you probably have a clogged heater core. Most times it is the blend door actuator.