Why does my air conditioner never cool my apartment to the temperature that I set it for?

Question

I have my thermostat set at 70 degrees. The air conditioner never shuts off because the thermostat reads 79 degrees. I do live on the top floor of my apartment building, which is essentially the fourth floor of the building. My maintenance person for my apartment claims that's why my apartment won't cool off. Further, when I shut off the air conditioner to save energy, I hear a "crackling" noise- like ice melting. Now that can't be normal...

I just wanted to clarify a few things:

1) I have only shut the unit off once in the last few weeks. It's been close to two weeks since I did that and the apt. is still not cooled off.

2) I do not have access to the AC unit as it is in the ceiling, screwed panel, etc. Even if I could get at it, I am not handy AT ALL! Therefore, I cannot clean anything in the unit. To my knowledge, my maintenance person does not do any regular upkeep of the system unless I ask. For example, I have to call to say that I can see that the filter needs to be changed. This occurs every couple of months and I'm not sure if they do anything else at the same time.

3) Other residents on my floor do not have the same issue with having to set their temperature lower because we're on the top floor.

Thank you for all the good feedback.

Answer 1

If ice forms on the heat exchanger, your cooling capacity will be way down. Sometimes that happens if the water drain gets plugged. Clean it out! ~
And a top floor unit will always be hotter.

Answer 2

Your maintenance person is quite correct. Being on the top floor exposes you to (GASP) the rays of the sun on the roof directly over the ceilings of your unit.

If you do not see water dripping from your unit when you hear this crackling noise, the noise may well be coming from the sealed refrigeration unit itself, as it slowly equalizes the pressure of the coolant gas from the 'high pressure side to the low pressure side'. If that is the case, the noise is normal.

Answer 3

Here are some possible reasons:

The filter may be dirty.
The Evaperator coils may be dirty.
The refrigrant may be low.
The Thermostat may be placed where a heat source is, eg. sunlight or draft.
You should check the output(where the air out comes out), it should read around 65 Degree.

Answer 4

your air conditioner is probably too small as far as Btu,an air conditioner should be bought according to how many square feet you have to cool,and also you have to compensate for the heat being on the last floor, remember hot air rises.