AC blowing warm air — refrigerant

Start with low-risk checks: thermostat set to Cool (not Heat), fan on Auto, and a clean filter. A completely clogged filter can make supply air feel warm even when the system runs.

How old is the filter, roughly?

Good step. Next: feel the larger copper line at the outdoor unit with the system running — if it is not cool to the touch after ten minutes, you may be low on refrigerant or have a compressor issue. Do not open the unit.

Any ice on the indoor line set or outdoor coil?

That pattern usually needs a licensed HVAC tech — refrigerant charge, metering device, or compressor diagnostics require gauges and EPA handling.

Use Notify my landlord with: new filter installed, warm supply air persists, suction line not cold, outdoor fan running.

If the apartment is above 85 and you have vulnerable people inside, say so — some leases treat that as priority.

Great outcome. Keep the new filter schedule regular and note any gradual loss of cooling over the next month — slow leaks sometimes need a second look.