My fan only works on the maximum position. Positions 1-3 does not blow anything out. I'm almost 100% certain that it's the blower motor resistor. I have a 2006 Nissan Sentra. Is the Blower Motor Resistor still located behind the glove compartment like is was in the older models? I'm replacing one this weekend & just needed to know if it's still located there. Is it still a pretty simple job?

There's a 10amp fuse that powers the ac clutch relay and compressor. There are 15amp fuses that power the blower motor and the ac control switch. All of those fuses get power from the key switch. The resistor and fan switch provide the ground circuit for the blower motor.
I would want to know if those fuses are getting power, and if the control panel is working. You should be able to ground the blower motor and make it run on high, and that should not have any effect on if the ac compressor is running or not.
It could be a key switch problem in that the circuit is not strong enough to handle the load from the blower and the compressor at the same time.

I would check all fuses associated with the HVAC, if all fuses are good and you are sure the new part you bought is good then the problem would be in the control unit.

You have got a defective blower motor resistor. Your blower resistor is located just to the left of your blower motor (which is located under the passenger side of your dash. You may find you have a carpeted covered piece of cardboard that is located on the underside of the dash (below the glove box ) if so you'll have to to remove it by removing the retaining clips, Now look up behind the glove box and you"ll see the blower motor and just to the left of it there is rectangular unit with a connector with six wires within the connector , the colors of the wires will be as follows (black and orange)(black and yellow)(two wire's that are black and white)(black and blue)and (black). the blower motor resistor is totally bypassed when you turn your fan speed to high ! The blower speed is controlled by the ground side of the blower. When you request any of the other three speeds the ground circuit is routed through the blower resistor which is made up of three resistors.( resistors reduce the current flow) and each resistor reduces a predetermined about of current.So when you request medium high blower speed the ground circuit runs through one resistor, if you request medium low the ground circuit runs through two resistors , and through three resistors to obtain low blower speed, Normally what happens is the blower resistor blows out the circuit between the fan switch and the blower motor resistor which results in the lost of all lower speeds,no different then the wire to the blower motor just being disconnected.Replace the blower motor resistor and you will in great shape .Thanks for using fixya

The blower motor resistors or fan switch itself are defective.
High speed has no resistors B+ goes straight to blower motor.

Yes I would go with the switch, BUT, does it have a resistor bank? That is, how does it reduce the speed? Many systems use resistors to lower the speed. Burnt or bad connections can cause this as well.
You can test the blower motor by connecting direct power from a source like the cigarette lighter if you are handy.
Most of the time the lower speeds konk out but the high speed continues to work this is the resistor bank that goes out.

It sounds like the blower motor is not working. If you don't hear it running when you switch it on, check the fuse first. If the fuse is OK, you will probably need a new blower motor. It could also be a faulty fan switch or blower motor resistor. Once you remove the blower motor assembly, you can test it by putting battery voltage across the contacts with jumper wires, making sure to get correct polarity. If it does not spin, it should be replaced. If the blower does work when removed, the fan switch is probably at fault. The resistor is usually indicated when the fan works only at certain switch positions, but not all.

If this occurs in all positions, check fuse, check for power at the fan motor, if power in all positions replace motor. if no power at fan and fuse is good, check blower motor resistor and blower motor control switch. Replace as required

remove dash insulator from under glove box. then move bcm to one side, fan resistor is beside the fan blower motor. the resistor will keep fan speeds from working. remove wiring and screws from resistor then take it out.

I dont know what the car uses , but it could be the resister if equipped , or relay. more than likely a relay on that year

there is a blower resistor located near blower motor and housing under glove box area it is one connector with about 5 wires to it and looks thin, held by two screws this resistor controls fan speeds - possibly it will look burned may even be hot to the touch so be carefully it is the most probable cause since you obviously have power to it and ground only being the fan speeds the problem.