The air conditioner won't work on settings1,2,3,4 but works on number 5 on full power. I don't know what it would be.

If the engine is not getting up to normal temp, I would replace the thermostat. Both heater hoses have to be hot to get heat inside the car.

How is it not working ?
No air blowing thru the vents ?
Air not cold ?
Is the compressor running ?

Get the clutch/brake fluid levels checked, as well as getting them to bleed the clutch. There might be an air lock in the hydraulic system. As always if you are in doubt take it to a known specialist.

Does it work if you tap it with it switched on? If so, then you have a worn out motor, and need to replace it.

Check power to the motor. If you have power, then replace the motor.

If you don't have power, then check the switch mechanism.

If power steering full of fluid ,then the pump is bad Turn the steering back and forth to get the air of the lines that mite help, if it don't it will be a bad pump. Know more about auto diagnostic tools for your car.

replace any soft hoses.
collapsed hoses cause water flow constriction
.that increases temp fast

to bleed air out of the system . if no air bleeder as such
with heater on full .-engine running
loosen the bypass pipe for the closed thermostat till only coolant flows no air bubbles
check if
the engine cooling fan spinning fast enough
the water pump in good condition
the interior directional flaps motors or actuators working

My air conditioner started blowing hot air last summer. I put coolant in it and didn't run it until the beginning of summer this year (2011). All of a sudden it started working again. Sometimes it blows hot but if I keep it running full blast the coolness comes back. I don't know why this happened.

That happen to me too i just fixed last week
the thing is that you have to change the fuse in infiniti there is 3 place of fuses first one is inside the car, Second one is infront of the battery and the third one is next to the battery so for the radio and A/C one is the infront of the battery open and change the fuse number 15 that will be fixed...

Thank You

Rahim Faiz

sounds like not enough freon or orfas valve is clogged. but most likely it is low on freon

my radio ad a/c works only same times for ten minute and then turn off and no works maybe until next day