'82 240d airconditioning ?

I'm the second owner of a prestine 1982 240d with 150k miles. Bought her 4 years ago with only 80k pampered miles on the odometer and all the dealer records. I'm proud of her and do my best to keep her mell maintained. A friend (heavy-equipment air cond. expert) converted my r12 to 134 and refilled my system for me. It lasted 40 miles, we found a leak, he repaired it and recharged my system. I was in a hurry so I had to leave without being able to figure out why the compressor isn't kicking in? Maybe I'm dreaming but is it possible there's a switch or something that I need to be looking for to get the compressor to kick back on? I can hear a click inside the car (or through the radio) when I dial the air to MAX, but it's not the compressor engaging. Any suggestions? Please...be gentle.

Oh, I forgot to mention that l never could get the air conditioning to get very cool. It's when the outside temp. is over 100 it barely helps to have it on- here's why...the compressor would shut-off just as the air was blowing cool. Usually it would blow cool for just a minute and then click-off for several minutes, then start blowing cool, but click-off, etc., consistently. It's nice I have a friend that knows air conditioning and doesn't charge me for the freon. But now he's stumped why the compressor isn't engaging, "this isn't a Caterpillar Tractor". I've got a great Mercedes mechanic too but he doesn't do air, and I don't want to just start buying components hit and miss. Any suggestions of where to go from here will be greatly appreciated.
Sweating in the Inland Empire- Temecula, CA, where it's been hotter than hot for way too long.