Need help troubleshooting compressor not turning on.

SOURCE: Temperature regulation

well the thermostats does regulate the temperatre wy cutting and turnng on the compressor, So its eighter that or the compressor,,,

SOURCE: coils freezing up!

Outdoor coils dirty creats high head pressure which in turn destroys a hermetic compressor for the fact that a hermetic compressor uses Superheated vapor to cool windings..Your post is so vague but for the fact you advise a service tech...

SOURCE: GE AGQ10AJ - Compressor not turning on

Most of the cases when tou heard a click on and off is aproblem with the compresor that goes off on overload, when the compresor try to start and is stuck , burned or the starting coil inside it is open it's overheat and goes off by the thermo bimetal switch.Also could be the capacitor, to check it you need a capacitor tester,but if you don't have it you can try to put anew one (no more than 10 $) and see what happend if still the compresor is getting hot and won't turn on it's burned, jamed or open , and you have to replce it ,if it's less than a year old it should be under warranty but if not is an expensive job and you better get a new unit.

SOURCE: AMANA PTH153B35AE PTAC Temp drop??

PTAC temp drop should be 20 to 25 degrees across the coil. They never put a service tap on these units. I sell Amana PTACs. You may be alittle low on gas. Check your air TD and that will tell you. The compressor may be overheating due to lack of cool gas to cool the comp. May need a service tech but get a free estimate first. Rus

SOURCE: not cooling very good anymore.

Your intuition is right, the ice buildup is why it's not cooling so well now: the evaporator isn't getting the correct air flow and surface area for heat exchange. The 1st thing you might want to check is to make sure that it's draining properly. The 2nd thing you might want to do is to check that the room is over 100 sqft. If you'r only cooling a tiny bedroom, the AC's basically oversized: your cooling already cooled air, so it freezes. The actual reason that is freezes is because the condition is just right for the immediate area near the evaporator to be at the saturation point. Think of it in terms of weather: warm and humid air collides with cool air and it begins to rain. The temperature drops further, and the rain turns into snow. One thing you could try to make it not freeze-up is to adjust the temperature setting a few degrees or change the fan speed.