Check the Coolant tank - look for stains from seeping - like around the ports.
This might indicate that the cooling system saw a big spike and vented out pressure, but it possibly also means a compromised head gasket too - from pressures inside the motor leaked into the cooling system and cracked open the coolant tank.
When you're in a parking lot, that Fan should operate several moments up to minutes and shut off, but if it's not and you're feeling and sensing the engine overheating - you can turn the AC on, if you hear the fan then,
then continue to use it in AC mode - its the only way the system can override that (possibly failed) cooling sensor fan system. But remember to keep the heat setting to mid-point - might make it uncomfortable but the issue is that the sensor is affected - it's not telling the fan to kick on.
IF you turn the AC on and that Fan doesn't kick on, Then Stop! Pop open the hood and find the engine compartment fuse box, the owners manual and look for the relay and or fuse to the fan - these need to be checked - pull the fuse and even swap the relays - see if the system can recover and use the AC - it's the only way the fan even can come on - to get you to some help and replace the relay as you can and swap them back to their correct positions when this threat is over.
- Additional note: This comes from experience, for if the cooling fan sensor does not work, the system will never know it's going to start overheating and cause a catastrophic failure - so the issue of "Why are you using the A/C?" is to override the failed cooling system that would have controlled the Fan. The normal cooling Fan operation it would otherwise normally have. No Fan and it's overheating is a sure sign of the sensor or Fan failure - even the Relay can fail - so another option is needed. The AC system works when the compressor is on, but the AC system also controls the Fan so if the Fan does not come on in using the AC the Cooling Fan and it's shroud need to be inspected and even replaced - for if the fan can't kick on - any warm 80F or above day will kill your engine simply from the heat it can't take away even at highway speeds. When you have no AC and the Fan will not work, then stop and get a tow to get serviced - it's far cheaper to pay that bill than to pay for a new engine.
