Does the maker have a 1-800 number? Have you received any useful advice from them? What capacity in amps is the circuit breaker? Is it fairly new or very old? As some circuit breakers age they get more sensitive and trip more easily. Which is better than the opposite possibility! Does the air conditioner cause the trip within a few minutes of start up or can it happen any time? Some air conditioners take a lot of power to get going and much less to keep going so a unit that is going on and off quite often is working harder. This can also produce a damp, cold, clammy feeling in the air of the room and is an indication that the unit is too big for the job. A smaller unit that runs constantly in high heat, high humidity situations is more comfortable. If there is no problem found with the apartment electrical system or the AC, then a smaller unit is likely the best option.

"The last time it acted up i checked and had the 24 volts coming from the thermostat to the board but no voltage from the board to the contactor which is what made me think a pressure switch may be locking the voltage out" I want to be clear about something... When you say "the board", do you mean the control board that sits inside your furnace\blower? If so, that's what I mean as well. That board does a lot of things (including the timed shut-off delay mentioned below) but as far as I know, all it does to turn the condenser unit on or off is sent 24 volts over two lines to the unit, specifically the contactor within the unit. There certainly may be more complicated control systems out there but that's the way traditional A\C systems were set up. In such systems, the control board has absolutely no idea of what any "pressure switch" inside the condenser unit is doing, no idea of whether you have no coolant in the lines, no idea of any sort of problem or situation that might exist within the condensing unit. When that control board wants to turn on the condenser unit, it simply sends 24 volts down those little wires. If you turn your thermostat down far enough to signal that you want the room cooler, the thermostat sends a signal to the control board in the furnace, which then turns the blower on by the coils, and then sends the 24 volts to the condensing unit. If in fact you have "no voltage from the board to the contactor" despite you adjusting the thermostat to start the cooling cycle, then your first concern would be to understand why the board or the wires from the board aren't working properly. If, on the other hand, you mean some sort of control board within the condenser unit itself, one that acts as a second brain (third if you count the thermostat) in the system and takes into account information from within the condenser such as high and low pressure readings before sending the 24 volts along to the contactor, then sure, you might well have an issue with that particular board or the pressure sensors or perhaps a whole bunch of things. Don't know. What I do know is that if you are indeed talking about this sort of internal control within the condenser itself and when you think it should be triggering the contactor but you can't detect any juice between the internal board and the contactor, then your problem isn't the contactor. The only way you can determine whether a contactor is bad is to send 24 volts to it. If you do that but the 220 volt lines within the unit aren't energized, then it's the contactor and indeed, because contactor issues can be all about carbon buildup on the contacts, you might have the symptoms you describe. But if the contactor isn't getting the 24 volts at all, you need to look for another answer. I strongly suggest that you turn this over to a repair tech given that you're no longer talking about replacing a $12 contactor in 15 minutes. Nick in Palm Springs

Check the unit Data Plate and find out the min breaker and wire size and make sure you have the proper protection. In general when an HVAC tech encounters this problem it is due to a loose connection in the main power being delivered to the unit. Look for wire that is discolered inside the unit. Tighten all connections....connections that are most suspect are the ones right at the breaker and outside disconnect. Then check the main unit contactor connections after that procede to the compressor and check those connections. This should be done by a licenced HVACR contractor

"The airflow I do not know. The last AC guy that inspected the system reported a liquid line pressure of about 270 psi (the suction line around 70 psi), that after he removed some freon. He said it was OK." "The outside T was around 86 F. The system is from 1996." (10 to 12-SEER) A 122.5°F is a fairly high condensing temp. What was the outdoor temp & what SEER or year would the condenser be? (my question) ----- That is a 36.5°F temp-rise off the condenser; that is way too high; 23 to 26°F would be considered high for a 10-12-SEER condenser. There are a number of things it could be. It probably has a fixed orifice as the superheat is not too high due to the high head pressure feeding the coil faster; could also be TXV controlling @14°F superheat. Check for a dirty condenser coil or the blower motor that is not achieving its rate rpm. If there are major supply duct leaks (temps @registers are very high) that could drop static pressures so low that the indoor blower is delivering too much air through the evaporator. It could have a major return-air leak from the hot attic area. It could be a combination of factors; not just or even two...