...fan blows but no heat? I have a 2004 jeep grand cherokee that has a heater problem. one day everything works fine switches, controls, heat blows, all the speeds and vents, but the next day theres no heat, the fan blows and switches work but theres no heat coming out of any of the vents (floor, dash, vents, etc.). Could it be just the heater control unit itself? If you have any idea what it could be let me know thanks