1990 Chrysler New Yorker heater blow not working

This is what you pay mechanics to diagnose. They will have the advantage of knowing if you have automatic climate control or a standard system. If it's the standard system they will do voltage tests to see if power is getting to the motor speed switch, then to the resistor block, then to the fan motor. If it has automatic temperature control, a computer is used to control fan speed. Those don't cause a real lot of trouble. If a fuse blows for the fan, it is because the bearings are tight causing the motor to draw too much current. The motor will usually run for a while on the lower speeds after the fuse is replaced, but it's going to blow again until the motor is replaced.