When you take your car for a car AC service, the technician starts by checking the cabin temperature while operating the AC. It should be approximately 5°C-10°C. They would then proceed to check the level of the refrigerant present in the system.
When the refrigerant level drops it affects the AC’s ability to cool. In fact, one of the most common reasons why the air-conditioning isn’t cooling your car properly is this. Using a pressure gauge and a precision AC gas recharging machine, they flush the refrigerant out and tops it up to the recommended level.
While working on this, they also check if there is any possible leak or crack in the AC line and hoses. The technician may use a UV dye to better pinpoint a possible leak in the system.