Those are actually technicians, and they have to because they know how, they know the laws associated with working on AC and refrigeration systems, they know the dangers involved with it, and they have the certification to do it.
engineers need to check air conditioning systems regularly to make sure that the air quality is good enough for humans to breath in.
If this is an air conditioner in a home or an apartment, check the circut breaker panel. If this is a automobile air conditioner, check the belt which drives the compressor, and the fusebox for a blown fuse.
There is no such product as an air conditioner window. However, you can buy a used window air conditioner on eBay or Craigslist. You can also check the classifieds in the local newspaper.
If central air conditioner turns on but is not blowing through the vents, check the filter. If it is dirty, change it. Change the thermostat into cool, this will defrost the air conditioner.
check fuse.
Check main breakers.
The most appropriate are those that are licensed by Samsung directly on a preferred engineers listing .
Run the fan and check all accessable ductwork,especially joints.
You can find air conditioner units from here : http://www.lennox.com/products/air-conditioners/ you should check it out. That's it according to my knowledge's. Good luck
You would have to recover the refrigerant and weigh it.
By using gaging instrument
If your air conditioner is not blowing cold air and you see ice on the unit, it may be frozen. Turn it off to thaw and check for any blockages or low refrigerant levels.