i tryed to adjust my heater and there is still heat coming through is there anything i can do??
can i add a shut off value under the hood in one of the heater hoses,, will that do anything to hurt the running hot of the motor??
You can install that, but you need controls in the car to run it. If you don't have them from the factory, they are not easy to do.
You could always just bypass the heater core for the summer, or find out through your heater box assembly what is leaking air. A properly functioning system should let hot air into the cabin.
Problem is, most factory valves are vacuum controlled, and your car probably doesn't have the vacuum switches internally. You may be able to find a cable one and do it manually, but that woiuld be a pita. Just bypass the heater core.