How can I replace the front blower motor on the heater?

Depending on make, model, F.A.U, or heat pump. If its a modern furnace it has a draft motor and a blower motor, older furnaces use natural draft and just have a blower motor, either or. You must turn all power off which it consist of 120V, if a heat pump it will consist of 240V. There might be a few screws, usually are 1/4'' or 5/16'', remove the screws and blower compartment slides out. (If draft motor, it will just come out.) There might be a few wires that need to be disconnected, sometimes they are color coded but if not, label the wires where they go on the control board or control panel. Once you have the blower compartment out, remove the (3)3/8'' screws on the side and loosen the set screw inside where the shaft is, then clean the shaft with sand paper and WD40, pull the motor mount out along with the motor, then replace the motor. You'll need to replace the capacitor as well. Depending on motor horsepower, capacitors range from 5MFD to 40MFD being the highest for single phase blower motors. Retrace your steps in order to place everything back, restore power and turn unit on, with an ampmeter check and see if you have the right speed for both heating and cooling (black is always high speed cooling only.) Good luck.