How do i know if the ac compressor is engaging in my 2003 l200?

Can you tell if compressor clutch is engaged? If clutch isn't engaged only the belt pulley will be moving and the compressor clutch is not engaged. If not engaged, no ac.

Can you check for applicable hvac codes? To check codes, your-self, at the least, you need an obd2 code reader, that will check manufacturer specific codes as well as po.

I haven't looked at your wiring, you could probably check voltage and ground for compressor, hvac on.
In the diagram, you see applicable fuses--clutch relay-- the top wire at ac clutch is voltage--black wire is ground.

Knowing make model and year would help. Most newer vehicles, 2000 and newer, will adjust the idle control up to compensate for the compressor engaging. Possible there is an issue in the idle air control valve or electrical circuit.

the compressor is protected by a pressure switch to prevent from damage of the compressor when ever the prion gas is leaking there no pressure on the system so the compressor will not engage check for the linking of the system

I assume it's because your clutch is engaging and disengaging. Could be from a loose electrical plug to your compressor coil on the compressor. It could be a loose plug to the pressure sensor or a bad pressure sensor because that sensor will shut it off if the car is low on Freon causing low pressure in the system. Could be low on Freon so it's on the edge of having enough pressure to turn it on and then shuts it down again because it dips below the pressure threshold when the compressor kicks in. Could be a bad compressor coil that engages the clutch. Maybe a loose connector to the AC Button in the car or the AC Button is intermittent. Could be an intermittent relay engaging the compressor clutch. That's a good list of what all could cause it and if you end up needing to replace the compressor, I made a video on how I did it.

Should be a electrical box under thehood labeled fuses and relays. Locate the fan relay by looking at the diagram underthe box and change it out, It unplugs.

When your R-134a runs too low it will NOT engage the compressor. You need to refill your a/c system before the clutch will engage, I also suggest finding the leak.

pls. check your ac compressor magnetic clutch attached in front of ur compressor if its working/ ac clutch engage when u turn the ac switch on and disengage when u turn the ac switch off/ it normally makes a clacking sound when it engage with the rotation of ur compressor/ if its not engaging it means ur magnetic clutch is stuck up giving excessive load to ur engine thats why it overheats/ it smell burnt because its magnetic coil is fried/ or check cooling system of ur car might be that coolant is empty/ fan is not working/ radiator is clogged or thermostatic valve is stuck blocking coolant flow....

Check A/C compressor relay. When you say it seems to be full of gas(freon) have you actually put a pressure gauge on the system? If the pressure is too low, the compressor will not engage. If the compressor relay is functioning, check for power at the compressor clutch. If it has power to it and it still is not engaging, the A/C clutch may need replacing. It is usually almost as economical to replace the complete compressor with clutch installed than to just purchase a clutch. Keep in mind if you replace the compressor you should also replace the receiver/dryer also referred to as the accumulator.

you havea broken cable to the vent blend motor or a bad vachum motor.

replace the black relay between the 2 blue relays in the fuse box. cost about 5 bucks.