Why did my air conditioner start blowing only warm air?

Sudden changes with A/C unit would indicate a mechanical problem, not just Freon. I would call a repairman. If the fans inside and out are working and the unit is over 10 years old that would increase the probability of a mechanical part failing like the condenser or compressor.

No, I not a repairman but have had issues before with my A/C.

I don’t know much about air conditioning, but going on my own personal experience, based off my air con, is the water out pipe clear? if not that can cause it to go warm.

@poisonedantidote where would I find the water out pipe?

@SuperMouse Ok… This is how my air con works…

I have a unit in my room that provides cool and hot air, this device has two pipes running out of it, the pipes go in to the wall, and outside of the house, the pipes are connected to a big air con devide with a big fan that is on the outside of the building.

One of the pipes leaving the house is carrying water that the air con has removed from the air, the water moves along the pipe to the big box outside, then drips out of a small pipe on the box.

If any part of this water out pipe gets blocked, be it inside or outside the house, my air conditioner will instantly stop giving off cold air, and will turn warm instantly.

I don’t know if you have the same model, i doubt it, i also dont know if you even have the same air con technology, but if you do, it is likely this is the problem. For me it’s the pipe or the filter, and you say you checked the filter, so im guessing pipe.

@poisonedantidote that makes sense, thank you! I didn’t see the pipe by the unit outside, but I know there is drain in the utility room downstairs and the pipe might be there, so I’m heading down there to take a look.

That hose could be frozen over, or simply blocked. That would cause this.
However, since you had the RE CO alarm, I suspect something else.
It’s either the freon, or the programming for the unit.
Call the repairman.

If you need freon you need a repairman that should be done professionally. Low freon would definitely cause such a problem, and you’d want to have a check done for why it got low.

The only other thing is, have you had any thunderstorms or power outages? If so maybe a fuse/circuit breaker may have failed/tripped. Thermostat would get a weird display and not work as intended.

We have had tons of storms should I try to reset the breaker?

Yes there may be an issue and a reset me take care of it.

Turn your thermostat to OFF before you do.

Recovery in Honeywell thermostats is part of its programming. It “learns” at what time you want your house to be a certain temperature and how long your system takes to get to that temp. Do you have it “programmed” for certain temp at certain times?
Is there a catch pan under the inside unit? Is it full of water? If its full of water, the system may be shut down to prevent flooding.
Re the outdoor unit, is the fan and the compressor running or just the fan?
Do you have two copper lines that run between the inside unit and the outside unit? One about 3/8 inch and one about ¾ inch diameter. If you have these lines, touch both lines. The small one should be cold and the large one warm. There should be a noticeable temp difference. If there isn’t a temp difference, it indicates that your compressor ins’t running.