Try pushing the control knob down sightly and turning it counter clockwise to ON position. If it won't turn, this usually indicates that the control valve has locked up. Turn the pilot off and wait 5 minutes, Relight the pilot and try turning it again, as described above. If it still doesn't turn easily, the Control Valve will have to be replaced. It's not an inexpensive part, as it's the heart and brains of the heater.
Also, DESA International the manufacturer of your Vanguard heater is no longer in business. However, some parts are still available. Do a Google search for Vanguard Vent-free Heater Parts and you may have some success in find it for your specific model number.
It's rare for a control valve to lock up or fail. It's usually caused by someone trying to force the control knob to turn with a pair of pliers and usually in the wrong direction. Which breaks the plastic gears inside the control valve. I'm not saying you did this, it's just what usually causes it.
Answers & Comments
Try pushing the control knob down sightly and turning it counter clockwise to ON position. If it won't turn, this usually indicates that the control valve has locked up. Turn the pilot off and wait 5 minutes, Relight the pilot and try turning it again, as described above. If it still doesn't turn easily, the Control Valve will have to be replaced. It's not an inexpensive part, as it's the heart and brains of the heater.
Also, DESA International the manufacturer of your Vanguard heater is no longer in business. However, some parts are still available. Do a Google search for Vanguard Vent-free Heater Parts and you may have some success in find it for your specific model number.
It's rare for a control valve to lock up or fail. It's usually caused by someone trying to force the control knob to turn with a pair of pliers and usually in the wrong direction. Which breaks the plastic gears inside the control valve. I'm not saying you did this, it's just what usually causes it.