bout to drive me nuts , from what I understand, a jeep heater almost shoots out flames they get so warm. I have checked all movment of the selector switches and vacuum modules under the dash, all operate to full out and full in. no vaccuum leaks. still no heat. checked the hoses while at running temp (209) both are good and hot. running aitn-freeze, good and clear with good flow. the temp. selector (blue to red knob) is electronic, could it have gone bad and not allowing the stop-cock to open? It does have a fantastic air conditioner on the warm days, and even a better one on the cool evenings ~grin~