[Razorback1980]

So here is how your heater works...The engine is full of coolant that runs between 160 and 200 degrees depending on the thermostat you have installed. Under your dash is a smaller radiator like the one in the front of your car only smaller ....it's called a heater core. As you are driving the hot water is pumped into the heater core making it hot and then the fan blows air across the hot heater core and that air comes into the cabin. Because the water is 200 degrees, you don't want the air to come into your car at 200 degrees, so they put a valve in there similar to a water faucet on the outside of your house that restricts how much water can come into the heater core. If you only want a little heat only a small amount of water comes in, so the heater core doesn't get as hot. As you want more heat, more coolant is allowed in and the heater core gets hotter. That's the function of the valve...to restrict the water flow. If you are real creative, you can put an inline valve in your line and increase or decrease the amount of water to increase or decrease the heat until the right part arrives....or you can drive with full heat...if you keep it on defrost, it shouldn't be too bad.