Where is the rheostat for the heater blower on a 99 toyota corolla and is it easy to get to

heater fan motor has a relay
or vacuum or electronic motor works the internal flaps

if it is the fan motor
how to replace one
2006 Toyota Corolla Removing AC Heater Blower

fuse panel on the inside of the car drivers side

Take it apart and clean it out as much as you can. Cleaner ( like lysol spray?) may help. Take the blower motor out-that should be easy to get to-and clean out that cavity.
It is the resistor pack, not the switch, for the blower speed problem. See if you can take the glove box off or out. Look for the resistor-it is somewhere on the heater case, and easily replaced. Only one or two screws that hold it, and the electrical connector, and it's free.

sounds like your rehostat is faulty, its situated near the blower motor in the heater box.

The Blower motor for the heater is mounted behind the glove box.

Yes could be the blower relay or loose ground in the blower circuit.
Try your local library they may have a manual with the cicuit diagram.

Why not check it in the car? It is under the glove box.

The Blower resistor needs replaced.

there should not be no more then three screws and unplug and the blower is out and you say its noisy check for leaves and to make sure the blower is not hitting anything before you go to buy another one.

The dimmer for the 2009 Corolla is the right-hand stem in the dash for the trip meters, rotate it to control the dimmer.