How do i replace heater moter

no specification of vehicle -generic answer - if external crack on pipe can solder carefully if core or pipes damaged then replacement will be necessary and depending on vehicle will be under dash rip out

Sorry I am unable to locate this diagram.

some thing in heater hitting the squirrel cage {fan blades }

Look in the owners manual.

Pull the dash out its in the heater box,but first check the firewall where the heater pipe,s go through the could be a plate to unscrew.

do you have power at the blower? does it work on any speed?check all fuses and relay. also, look into the blower motor resistor, located next the the blower itself

Blower moters are usually good for about ten years. If you can run 12 volts directly to the blower moter and it wont run. It will need to be replaced

From you're description I'd say the blower moter has
cooked a bearing. Check fuse #1 and #2 both are 15amp. They're in the fuse block behind the coin tray
on the lower left side of the dash. They usually go first if the bl moter locks up. To do a quick test unplug the bl moter, located behind the right side of
the dash. Turn the fan switch off and replace the fuses. Plug the blower in and turn it on, if it pop's the
fuses again replace the blower moter. Hope this helps.

if the blower motor won't turn on try replaceing the blower motor resistor located on the heater box under the hood

replace the fan resistor located on the side of the heater box under the dash usually on the passenger side this controls the fan motor speed along with the switch itself.