Mercedes: 190E MERCEDES, 190e mercedes, leak location

Question
I own 190E 2.0 1993 model petrol,1.When I Swith on the head lights the AC konb turn too hot to touch.2.over the last 40 days I filled the ac gas two times .Because the ac is not cooling properly and the gas might be leaking. I took to the mechanic. He says the gas might be leaking and hence there is little gas ,and ask me if the same issue continues you have to change the bottle like thing  he shown where the gas can be seen through glass which is visible just down and and also a valve,some where just behind the ac knobs. Please advise.
regars,
SYED.

Answer
The A/C knob getting hot = someone has installed the wrong bulb = it is melting the inside of your knob when lights are on.

Recharging the A/C system indicates there is a leak in your system, leak location unknown = this needs professional attention.