Why is my apartment still 88 degrees even with two ACs running?

Portable units are notorious for over-promising on those BTU ratings because they don't account for the massive amount of heat radiating off the exhaust hoses. Even with a dual-hose setup, those plastic tubes are basically **giant radiators** sitting inside your living space. If you have five or six feet of uninsulated hose exposed, you’re essentially running a small space heater at the same time you’re trying to cool the room. You shold grab some reflective bubble wrap insulation or wrap those hoses in thick towels to see if it makes a difference. If you can't touch the exhaust hose because it's too hot, it's definitely dumping heat back into your 88-degree apartment. Also, check the distance between the intake and exhaust on the window kit. If they are too close togehter, the intake might be sucking in the hot air that was just exhausted, which kills the efficiency.

Another factor is that portable ACs are really only designed for single-room cooling, not an entire 660-square-foot floor plan. Air doesn't naturally move around corners or through narrow doorways very well. Unless you have high-velocity fans physically pushing that cold air from the units into the other rooms, you're just going to have a freezing 5-foot radius around the machines while the rest of the apartment stays a furnace.

Since the place is already 88 degrees, you're fighting **thermal mass**. Every wall, couch, and floor joist in that apartment is holding onto that heat. And it can take 24 to 48 hours of continuous running to actually pull the heat out of the physical structure of the building before the air temprature starts to drop significantly. If those units haven't been running for two full days straight, they probably haven't even finished cooling down your furniture yet.

Stop running that old 12k unit immediately. If it's a single-hose model, it's creating massive negative pressure, essentially sucking 90-degree air from the hallway and wall cavities right back into your space. You're basically sabotaging the dual-hose unit's physics.

I’ve seen this with the Whynter ARC-14S setups before. Even a beefy 16k BTU SACC rating can't keep up if you're forcing an air exchange with the outdoors every ten minutes. Stick to the new unit alone, keep the doors shut, and check your Delta T. If you aren't seeing a 15-20 degree drop between the intake and the output vent, the compressor might be short-cycling.

Totally agree on the negative pressure issue—that old unit is defintely fighting you. Another thing to check is how much slack you have in those hoses. If they're all coiled up or have sharp 90-degree bends, you're killing your airflow. I found that shortening the exhaust hose to the absolute minimum length made a huge difference in my setup. Every extra foot of hose is just more surface area radiating heat back into the room, and those bends create backpressure that keeps the hot air from venting efficiently.

I'm super new to this, but what about your windows? I read that if you have alot of sun hitting the glass, it's like a greenhouse. Are your blinds shut or do you have blackout curtains? I noticed my unit struggled way more when the sun was hitting the glass directly. Also, is it possable the air is escaping under the front door? I put a towel under mine and it seemed to help, but I don't know if that's actualy a real thing or just in my head. Does the seal on the front door matter as much as the window kit?