AC/Heating fan does not work at lower settings

sounds like the fan resistor there should be a set of resistors near the fan under the dash on high speed, the lowest resistance setting is being used at lower fan speeds, higher value resistors are placed in the circuit, and it is these that have failed. you should be able to replace the resistor pack at reasonable cost, with minimal difficulty

This is not eawsy, but you can do it.

On MOST Toys, there is a 'resistor farm' in the fan housing. You have to pull the fan out of the airbox under the passenger's side of the dash. Note, it MAY be in the switch, as was in my old Celica, but this was unusual.

Ten MM socket, remove three screws and the connectors and drop the fan assembly down. It is typically NOT easy to do!

When you get it out you will see what looks like 3 springs. These are the resistors. Look carefully, one or two will be burnt or broken near the base. If you're patient and have a soldering iron, you can GENTLY clean the break with enery cloth or fine sandpaper and resolder it, try it before you reassemble! This is the cheap way out and may break in the middle of the winter when it's -40, or it may last for a year or two. Try a junkyard, these things are all over tha place and can be used from about any Toyota. A 3 speed fan will have two or three, a 4 speed fan will have

Or buy one from Toyota for about $45...

Wow! When mine went, I had another car for parts, so fixing it was easy.

Good tip though!!!