Red light next to temperature gauge is on and flashing from temperature to F1- is this indicating the coolant fluid is low?

Obviously it's temperature gauge light. Check for coolant level first. Then check for coolant leak. If coolant is leaking out of your car, the lower coolant levels in your engine will cause it to overheat. If you have your heater on and it starts blowing hot air instead of cool, your engine is low on coolant. This will cause to flash a warning light on your car's dashboard.

Is the temp gauge not moving at all even after driving the car ?
And have you checked the coolant level in the radiator and the overflow tank ?

Some cars have a sensor in the coolant overflow tank. If you look at the tank there should be a low and full mark. Make sure the fluid is between the 2.

The blue light is only supposed to indicate low engine temperature, reminding you to go easy on the engine until the light goes out.
The flashing is either for low coolant or for overheating, and it sounds like you are having a low coolant problem.
If after you add coolant the lights comes back, you have a coolant leak. The most common place for a leak is the coolant flange on the end of the cylinder head. If you take the engine cover off and look at the area where the transmission meets the engine, you should see either pink coolant puddling or pink crusty residue.
It's also possible to have other leaks from the radiator, heater core, water pump, etc. The nice thing is that with the pink coolant it will leave a trace of pink residue leading to the leak if you take a good look around with a flashlight.

• Full instrumentation pack (four ancillary guages plus tachometer) - with volt meter & oil pressure guage.
• Speedometer, odometer, tripmeter, fuel guage & water temperature guage standard in addition to the above.
• WARNING LIGHTS: High beam, rear window demist on, turn signal / hazard light, alternator fail, lights on, park-brake on, washer fluid low, radiator coolant low, cruise control indicator and low oil pressure.
• AUDIBLE WARNING CHIMES: low fuel, lights on, low alternator charge, low oil pressure, high coolant temperature and brake failure.
• Trip Computer standard featuring fuel consumption figures, distance to empty, average speed & time display.

I found this site, no mention of the fan in a cylinder, but I'll let you figure it out. Hope this helps.
http://www.trueblueford.com/ed_pages/EDfalcon_fairmont.html

I have seen this happen to a few cars when they were running REALLY low on coolant (anti-freeze) AND/OR had a major air pocket trapped in the cooling system.
Heres whats going on:
The gauge is driven by a temperature sensor that sticks into the cooling system. When your really low on coolant, some times the temperature sensor is exposed to air, instead of liquid coolant and the temperature of the sensor drops. As your driving around sometimes liquid coolant touches the sensor and the temperature reading will spike again to normal readings or to an even hotter reading then normal (because what little fluid is in the system is not enough to maintain proper temps).
If you recently filled up or topped off the coolant from a low coolant situation then you may have a major air bubble locked in the system, although this is far less likely in the small Sentra cooling system, but you never know.
Lastly, the sensor itself or the plug into the sensor is loose, broken, or shorting. You or someone you know can try to locate the coolant sensor for the gauge and see if the connect to the sensor is loose or the wire have become damaged, giving you readings all over the place.
nissanhelp . com is a great place for help and you can find factory service books on there. You can join for free and ask questions.

does it look like a radiator? Low coolant sensor, may be in the overflow tank. Check your coolant levels when cold.

A red light indicator may signify a hotter temperature, but may not necessarily indicate an overheating condition. A couple things can lead to this condition - low fluid level (check the fluid resevoir), the wrong coolant being used previously, a weak or failing water pump, a plugged or partially plugged coolant radiator, a bad fan, or a bad thermostat. I'd personally check the coolant first, usually needs to be replaced at about 100,000 miles or so, then check to see if you have any leaks if the fluid level is depressed. Then allow the car to operate from a cold start in the drive while observing the performance under the hood and compare it to the dummy light.

Hope this helps.

take the cap off of the radiator (whil engine is cold) start and run the vehicle. keep runnig 30mins after the vehicle is hot keeping notice of the rad fluid level.
keeping the cap off will prevent the pressure build up that woiuld keep the air in the system, keep adding water or antifreeze as the level goes down. this may take an hour or so.
also with the cap off, you will be able to see if your water pump is operating correctly. you will visibly be able to see movement in the rad when the pum is engaged.

Sounds like a CPU problem. your radiator may need a good flushing a s well. i would also check the heater core for any unusual problems like seal break or leakage.