When your AC compressor is cycling rapidly (cycle means turns on/off) it means the system STILL have refrigerant but not enough. Normal FULLY CHARGED system behaviour is that when the AC is NEWLY turned ON the compressor stays constantly ON until the cabin has sufficiently cooled down. Only after this the compressor would start to cycle to MAINTAIN the temp.

What you need to do now is to TOP UP the system. The video shows vacuuming process which is not needed in your case as your system has some refrigerant left. Just top it up. If you replace any AC component which require you to open (expose) the system to air then you need to vacuum down the system like in the video. Another reason to vacuum down the system is when you want to refill by weight like in the video. This BEST method of refilling R134a however is NOT for your case in which you're unsure of leaks in the system. It is wasteful effort to accurately weigh the refrigerant in just to have some loss later.


To answer your questions:
Q1: Yes. Use your manifold gauge set to TOP UP the system. Top it up until the compressor stays constantly ON. Always top up SLOWLY to avoid overfilling the system. Add another canister if one not enough. Open all windows, AC blower max and heater knob to max cooling. When compressor stays constantly ON, stop refilling (shut the BLUE valve) and read the BLUE gauge. It should read between 35-45psi depending on ambient temp. Ambient temp 70F should read about 35psi, ambient 90F should read about 45psi. Cold air should come out from the vents. Stop refilling. Now APPLY soap bubbles to all AC pipe/hose connections to look for a leak. If you find any THEN you need to repair the leak and vacuum down the system like in the video.

Important note: Do not use any quick resealing method (i.e. AC stop leak solution/mixture) to mend the leak. It could play havoc with the fine channels within the compressor and disrupt compressor lubrication. Repair it using the old school way of dismantling the leaking part and replace. This may mean a lot of extra work now but its for your long term benefit and peace of mind.


Q2: Most effective way to look for a leak is to use an AC dye. Its a specially made fluorescent dye to be injected into the system using specialised syringe tool. This way you don't need to evacuate the AC system empty just to inject the dye (remember the system is under high pressure). Leaking point is shown at where the dye leaks. The soap bubble method only shows immediate leaks. The AC dye method is for immediate AND long term leak detection. The dye stays circulating in the system for many years to come.


Regards,
Amarin.