Wondering why my compressor for my split system not running while my inside unit is

Could be a lot of reason why compressor is doing that .First make sure your outside unit is clean ,if not wash coil with water .If coil is clean check capicator and replaced if bad .if capicator is good then you might have a bad compressor or a leak in your system and compressor is shutting off on low pressure .
To figure this out you need to install your refrigerant guages to check

If there is 3 indoor units from one condensing unit
(6 pipes at outdoor unit) this is classed as a multi unit

All units will run correctly as long as they all require same mode, cooling or heating, if one unit decides to heat it will shut down until master unit decides to heat then it will start, for each unit to individually heat and cool there would have to be 3 pipes to each indoor,

it sounds like a wiring fault between your evaporater and condensing unit or your inside capillary sensor is damaged

Check the 24 volt wiring from the T-stat to the outdoor unit. Make sure the T-stat is actually calling for cool.

you can check your heat pump on the outside by turning off the power and listening to see if it makes a whoosh sound. and then turn it back on you should hear it kick in. Is the outside unit running? Sounds like an electrical problem maybe in the breaker or the contactor on the inside of the unit. This is where the 24 volts from the thermostat call to the 240 volts to kick on the condenser fan and compressor. Be real careful in messing with this because of the high voltage.

There couild be a small blockage in the refrigerant piping. This obstruction could be cyling through the system and causing the pressures to increase and decrease which is overheating the compressor. Normally when the compressor is overheating there is not enough refrigerant getting returned to the compressore to keep it cool while running. When it shuts down the the refrigerant equalizes which can return the blockage back to the coil or just simply dislodge it frome where it is hung up. When the compressor returns to its running temp, it turns back on and can cycle that blockage through the refrigerant piping which sometimes it may go thru and sometimes gets hung up and clog the system again. I would have a certified technician come over and hook their manifold to the system which can easily tell them if there is a blockage or he can trace the problem. Do you know what type of metering device is in the coil inside?

First check your circuit breaker or fuse that supplies power to the outside unit. It's probably separate from the inside unit. Then try to turn unit on. If the fan and compressor just make a humming sound then turn it off and check the capacitor if you have a multimeter. You can also look at it and see if the top looks expanded. That's a good sign its bad, but not all bad one's look expanded. Tomorrow I will have access to an LG service manual and can let you know what the code means. Sorry I can't get it sooner. Let me know what you find.

The most common reason is that the electrical power is not supply to the air conditioners. If the air conditioner operate for period of time then only it trips. Then , it could be possible that the MCB is under-sized. Please check the recommended MCB size.
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Your condensor fan motor has more than likely gone out. This fan should run at all times when the unit is on. Since the fan isn't working then the motor must have gone out.

Dave

is the compressor actually turning over ?? if not check the contactor, or capacitor is actually ok...

if it does turn over, are the stop valves open ??