The fan switch for the ac & htg was only working on high. Now it is not working at all. Is it going to be the switch or fan motor>?

a few things blown fuse--relay--shorted wire

I'm going to start from the beginning.
The blower motor gets power from the high blower relay and it is grounded thru the fan switch and the resistor. So you should have power on the pink white blower wire coming from the high relay to the blower motor. The orange black wire from the motor is ground going to the resistor and fan switch. The blue wires on the control panel are for the ac compressor.
The high blower relay gets power from fuse number 5 in the box. The blower motor is grounded thru the resistor and then thru the fan switch.
Photo courtesy of AutoZone.com

Yes, it is possible to install a thermostat backwards, though unlikely. If the thermostat isn't opening properly, the hot engine coolant won't be flowing over the cooling fan switch and give you high temps. I would first determine if the thermostat was opening at all, and if it is, is it opening at the proper temp. I have had many new thermostats that, while new, didn't work correctly. To check the cooling fan motor, turn on the AC(if equipped) and the fan should engage. If no AC, disconnect the cooling fan switch, and the fan should engage. Check for power and ground at the fan motor. If you have both power and ground, the fan motor is faulty

you probably need new control switch.

the ac resistor is bad

Most likely neither. The most common cause is that an electrical device called the blower motor resister block, has failed. This device provides all the slower speeds. It is generally mounted in the HVAC [Heating, Ventilation & Air Conditioning] box, very close to the blower motor. FYI, we mechanics call the fan motor inside the cabin the blower motor. The electric fan motor behind the radiator is called the cooling fan motor.
If the resistor block is OK, then you have either a bad fan speed switch or a melted electrical connector at that switch. 95% of the time, the resister block is the problem.
Charlie

Sounds like the blower motor resistor module is bad. It is located behind the glovebox and mounted to the blower motor. Open the glovebox and in the back left corner find a spring, push on spring to release glovebox door completely. You should be able to see blower motor and resistor module.

Sounds like the cooling fan motor,or motors,are not working.Check the relays,and fuses for the cooling fans.If the ac is on,look to see if the cooling fan,or fans come on.If they do ,then most likely have an enternal ac system problem.The expansion valve is the most likely problem,or possible,the dryer.Have the ac system checked to see if it is low,or if the low side is going into a vacuum,if it is going into a vacuum,replace the expansion valve.First check to see if the cooling fans are working with ac on.If I can help,let me know.>>>[email protected]

It sounds like your cooling fans are not working.Need to check the cooling fan fuses,and the cooling fan relays.There is also a high side switch mounted somewhere on the high side of the ac system that cuts the fans on,or kicks them up on high speed when the ac system gets to high on the high side of the system.This switch may also cut the compressor off.I would check the fuses and relays for these fans first,this is more likely the problem.Is the car running normal temperature? If not the fans may not be running at all.Have them checked.The fan or fans may be bad them selfs.If I can be any more help,let me know.>>[email protected]