Inside fan does not run on 1,2 but does on 3,4

check terminals on the ECM
the circuit is when the coolant temp sensor ( not the gauge sender) reaches a predetermined setting , power is supplied to the ECM which in turn activates the fan relay and switches on the fan
there are normally 2 fuses in the circuit
the gauge sender is normally a single wire unit and the sensor unit has 4 wires to it

the belt that touches the fan is the fan belt on all cars,
i guess you are asking about electric fans?
there are 2 on some cars, or even 3.
the front fan is the A/C.
the inside, is radiator for engine.
all 3 are needed if running AC.
the book on this covers all this in spades.
RTM
http://www.scantool.net/software/alldata-diy-1-month-subscription.html

Check fuse number 23 (20 amp) and fuse 12 (40amp) in the under hood fuse block. If you look inside the cover the fuses are typically labeled cooling fan 1, cooling fan 2 or something similar. The relays should also be labeled high speed and low speed cooling fan or something similar.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

First thing is to be sure that you are using 1/2 water and 1/2 antifreeze. Second is to be sure the thermostat is working, third is to be sure the radiator is not clogged inside or outside.

if the fan is running inside and the environmental controll is set to cool the AC compressor under the hood a click is heard and the compressor should start, it should cylcle on and off periodicly , if this dos not happen Have your AC system checked.

It could be one of several problems -

1) Failed compressor relay
2) Failed compressor
3) Failed component in the defrost system
4) Bad door gaskets
5) Failed door light switch

Questions to answer -

1) Was the compressor (large black domed item with three tubes (one stubbed) at the bottom back of the frig.) warm or hot?
2) Was the condenser fan running?
3) Was there thick ice buildup inside the louvers of the back wall of the freezer?
4) Was the fan running inside the freezer?
5) Look up my "Tips and Tricks" article on testing your door gaskets.
6) Open the door slightly and look inside as best you can. Is the light on or off? Continue to open the door until you see the light go on to confirm the light switch is working.
Your response will give us an idea where to look to find the problem.

Here are the possibilities: 1.radiator cooling fan switch (one of 2 types are listed for your yr. and model-one is mounted inside the thermostat housing, or engine mounted, not sure which you have. 2. Radiator cooling fan relay-located under the hood in fuse/relay box. 3. bad cooling fan motor. Don't run the car until you fix this, as you risk blowing a head gasket or trashing the engine.

The Thermostat / control board is located inside the vehicle right under the glovebox ( in fact un-hinge the glove box for a better working angle ), the board is right on the fan itself. There are ( 2 ) screws holding it in. A new board can be ordered thru CARQUEST for about 15.00. Their new model dosen't contain the small surface mount resistor that originally blew out. You cant repair the board because it's coated in epoxy "potting compound". If none of the 1 thru 4 levels on the fan work it's either the relay ( in the relay box in the engine compartment ), or the fan. If only a few of the 1 thru 4 levels works, then it's definately that control board.

Sonds like the fan to me. Yes, those are available separately. Water pump is internal inside of the timing cover and those are pretty bullet proof. Fan is most likely NG. Not that common. I have replaced only 1 in 12 years with Nissan.

fan Relay behind glove box or bad fan motor