It's my guess that it's shutting off due to high head pressure. It will usually run for about 10 minutes then shut off for 1-5 minutes. It is currently 11:30pm outdoor temp is 75 and the system is struggling to get to the set temp of 74. So I guess it isn't cooling as expected. I noticed during the hot part of the day the best temp drop it could do was 10 degrees. The air feels cold coming out of vents and the low side line is ice cold while the high side is warm.
I don't know what a dual coil means as far as the AC goes. Do you mean on the outdoor unit? I only notice one coil that wraps around 3 sides of the unit.
Tomorrow is a last ditch effort I am picking up coil cleaner and cleaning the compressor coil and the evaporator coil. Even though the outdoor one looks okay. I haven't inspected the evap coil yet. I am not sure if a clogged evap coil would cause high head pressures or not. The other thing will be to check if it had to high of a charge. The low side is at 70 on a 90 degree day and when water is sprayed on the outdoor coil the high side drops and stays at 250-275. As soon as I stop spraying the water the high side increases back to 350ish. I imagine it goes higher than that and eventually trips the high pressure safety though.
I am an aircraft mechanic so I understand systems, but this one has me stumped.