It is has many names, auxilary electric fan, condenser fan, AC fan. Basically its in front of the radiator and it helps to keep the condensor cool by drawing heat away from it. Without it running, the AC is very inefficient especially in hot weather like over 85 F. I know the AUX fan is controlled by the FSR and other things, which is why I will replace the FSR first. But i have yet to find a post about an aux fan coming back to life after replacing the FSR. most users experienced erratic fan behavior, but mine simply does not go on anymore.

I did some research and found out that if you pull the plug off the pressure switch on the A/C line the aux fan should run. (Thanks rjs1222). Can anyone else confirm this as a way to test the aux fan? Also if I am getting cold air on the left side, does that mean my compressor is good? I really hope I do not have to change a compressor

FSR/FSU does not, according to any wiring diagram I have, control the AUX fan. The FSU controls the blower fan for heat/AC. (The fan blows air into the cabin.) The FSU controls the on/off/speed of the fan.
The AUX fan is in front of the radiator and blows air through the radiator to cool it. It should be on with the AC and may run for a few minutes after the engine is switched off. both the relay for the AUX fan and the AUX fan motor are known failure points.
There is an old post on the subject of cold one side, hot the other. It might be worth searching for it and seeing what Weasel and others said in there as to the cure for the problem.

Well then what causes the aux fan to stay on when the car is shut off. This used to happen to me as well as other members on this forum. Most people said it was the FSR

A low AC charge will cause the aux fan to act up. Have you checked the pressure at the AC low pressure port? When my reading drops below 30 psi the aux fan will slow/stop, over 35/40 psi it runs like a date raped ape.

A bad FSR causes the blower fan to blow erratic and sometimes run when the ignition switch is off, not the aux fan.

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My pressure level was 45 psi, but the aux fan is off so the pressure would read higher. So how do I know how much to add? I do not want to overcharge it. Is one can too much?

The AUX fan in SOP will run for as much as minutes after the vehicle is shut off. Some people throw out FSR/FSU as the reason for every AC woe. It's like an automatic reaction.
The TOTAL charge for the system is just under 1 can from all accounts. If you need to recharged then you must have a leak. I had to replace the Service Port (High & Low) seals some years ago. The OEM seals were revised and a kit issued for older models so that standard "O -rings" can be fitted from then on. Cost was $11 per port or so then.
I took it to an AC repair shop. They found the leak and installed the new seals that I supplied, vacuumed out the system and recharged everything with the proper amount of "freon and oil for $95. Worth it when you consider the price of other parts should the recharge be done wrong!