The air condition in a 1987 300SDLMer.Benz ,once it starts, it will run all the time in high heat.?

At times, the air will not come on. In cooler weather, about 70-80 degrees, I hear a ticking sound coming from the front console on the right side. When the car is at operating Temperature, it goes away. I think it is due to the tech piecing the wires that he checked to see if they are OK. It only ticks when it is cool about 70-80 degrees outside. Sometimes(here in Tx), When it get around 100degrees, the air works, other times it does not.Once it starts working, it continue to operate and it is comfortabel in the car. I had a slight leak at the base of the compressor. I had the tech put a stop leak in the system. Once it start working, it get cold in the car at 100+ degrees. Help!