First, I feel your pain. I'm in Houston at my girlfriend's place; we live in a single family house, and the A/C is running all day even with the thermostat at 84 degrees. I work from home, so I can't let it go up higher than that. Our outside thermometer recorded 106 degrees today.
The things that we've added to the house to help keep cool, besides new insulation and having the A/C unit checked, include a bunch of things. First, a little theory. Your apartment heats up because of the sun heating the building primarily, and secondarily because of infiltration from the outside of warm air.
I'm going to just assume that your landlord isn't willing to replace your windows and doors with low-E dual-paned units. I've done this to my house in Bryan, TX and it literally cut my utility bill in half.
The first thing we did with her place, where the landlord is also not willing to rip out a ton of windows and replace them, was to get blinds with reflective shades in all of the windows, and external solar shades or screens where possible. Remember: Black stuff is OK on the outside of the structure, because black absorbs heat (and you don't care about the heat if it's on the outside) -- and white things on the inside of the structure, because you want the heat to not be absorbed and to just be reflected back out.
The second thing we did was to get a better thermostat for the house. The old one was a manual one with mercury in it; the new one has a digital timer and a bunch of other features that include breaks for things like the compressor coils to defrost.
The third thing we did was start replacing the A/C filter frequently... at least once a month.
It might help to suggest more if we knew what kind of A/C unit you have (is it one of those high-rise below-window units, or a 'real' one with a compressor and air exchanger in a closet or attic?), and what kind of structure (concrete or wood frame) you're in.
This problem can be multi-faceted. Someone could guess all day long as to what the problem(s) is / are and not even come close. Air conditioning isn't something to guess at. It's like having a rattle on a car and taking the approach of replacing one part at a time to find the rattle. It would be cheaper to just buy a new car. ( I give that as an example you can easily understand. You probably won't like it but the truth is always hard to swallow when it involves money.)
This is why air conditioning is a billion dollar plus industry. It's unlikely you will solve this kind of problem on your own as a "do it yourself" solution.
Sure you can do the things suggested like window coverings but if the problem is a "system performance" problem it's unlikely to make much difference.
With all of this said... if the problem isn't found and corrected it is quite possible to spend all kinds of money wastefully. The air conditioning business isn't known for being "easy". Certainly some repairs can be but issues such as these can be quite difficult.
It's quite possible it's just too hot. If out door temps are up over 110 degrees and you're hitting 76 inside... well if you think the AC is not working go outside for 15 minutes or so and walk back in. That dial on the wall is to turn the unit on and attempt to hit the desired temperature that you set. But there is no guarantee that it will. Air conditioning (depending on climate, location and design of the system) is mostly designed to lower the temperature 20 degrees from that of outside. (again this depends upon design of the system.)
Air conditioning loses noticeable capacity at 105 degree outdoor temp. again depending on climate and design of the system. Air conditioning isn't a cookie cutter appliance. One size does not fit all.
If out door temps hit 110 or more, be happy with what you get and reduce indoor loads. Plasma TV's, specialize computer equipment, excessive incandescent lighting, halogen lighting, excessive people loads (more than two per room), etc. will only add to your discomfort.
I am a licensed HVAC contractor with over 20 years experience in Residential HVAC systems. Serving the Katy & Cypress Texas area (suburb of Houston)
Best Answer
Yup, that's normal for mini-splits. It also keeps the room air circulating, which is especially important if it's used as heating - hot air will accumulate near the ceiling, so it blows it back down to the floor.
That unit has a variable speed fan motor, so when the unit is idle it's likely at minimum speed - probably single-digit watts.