Altima blowing hot air AC

There are a lot or reasons. Here is a post. https://gobdp.com/blog/car-ac-blowing-hot-air

TO MANY REASONS FOR IT TO QUITE WORKING IT WOULD BE BEST TO LET SOMEONE LOOK AT IT

Well thinking about the problem there e a flap in the vent pipes to shut off theatre and ac unit perhaps something has got in the pipe and stopping it closing or perhaps your heater control is US and needs replaceing . ( but I take it you have turned your heater to cold )

if the ac system is very strong and there a lot moisture in the air the a'c evaporator core will freeze up and stop air flow threw the cold core only use the recuiculation part to cool the car down about 5-10 min the turn the recuit off

I would check the following possibilities:
1. Is compressor clutch working? - You need to do this when the ac is blowing hot air only - locate compressor drive pulley on engine - rubber belt wraps around it. Start engine and set to max ac. When the ac is blowing hot air, look at the center of the compressor drive pulley using a good flash light - watch it for a while, it should be spinning with the pulley - this means the compressor is engaged. If not, the compressor is not engaged. If your ac is blowing hot air, then the compressor should be engaged and running (trying to cool). If it is not engaged, then your compressor clutch is probably going out. Could be low voltage to clutch, but more likely the clutch is worn out and only working some of the time. Note: if working normally, the compressor clutch will engage and disengage in cycles- but the air should always be cold. If clutch is bad, compressor would need to be replaced (sold as one unit). This is tricky to diagnose and could take some time - you need to do it when ac is blowing hot air but set to max cooling.

2. Low on refrigerant or refrigerant has moisture in it? If your ac blows cold initially after being off for a while, then heats up, and continues to regularly cycle back and forth between hot and cool air, then the system may be low on refrigerant or the refrigerant may have moisture in it that is freezing and restricting refrigerant flow. An a/c shop can check refrigerant level and even replace refrigerant if moisture is suspected.

Could be other issues, but I would start with these.

Good luck

your ac compressor is freezing up try not putting it on cold all the way. put thermostat towards the red jus a lil but still on the cold side to see if that helps

the blend motor on the vehicle is probably bad

Your AC is low on refrigerant; The AC compressor needs a minimum amount of regrigerant to run. If and when it does run (while low on refrigerant) the air coming out of the vents will not be cold. The refrigerant you require is R-134A and is available over the counter but if you are the least bit unsure as to how to add refrigerant, taking it to a garage that does AC recharging would be your best play. If you want to try to add refrigerant on your own you will need the following, 1LB can of R-134A, an AC hose adapter to deliver the refrigerant, and preferably an AC pressure guage to ensure you are not overfilling the AC line which will damage the system.

On the bottom of the air unit is the lever that changes temps. It likes to fall out of place.I propped mine back with a piece of half-inch copper pipe a couple of years ago.Remove glove box then panel on front side of console to access.

Sounds like your temperature actuator is not moving or your temp door is broken. On max a-c ,coolant is shut off to your heater core allowing only cold air in.