Just getting started , a few questions

[crshbandit]

Hi all! I just purchased a 1986 Toyota Supra, my first ever. Car has some miles on it but I have all the maint. records from the car and the body is not in bad shape. I am just starting to put together a list of things that I need to work on mechaniclly with the car. The first problem I want to try and fix is that the heater blows hot air all the time! The blower speed adjustment seems to work fine, but the heater seems to always be blowing out hot air. Where do you think I should start with diagnoseing this prob? The kid that owned the car before me put on an aftermarket muffler, so I would like to replace that also, kinda loud for an older guy like me. Thanks for any help and I am looking foreward to getting into this car, I always wanted one, I already took my 77 year old mom for a ride and she loved it!!