Well, the ac condenser is attached to the front of the radiator So spraying water on the front grill sprays the condenser will promote evaporation cooling. Air Conditioner works by taking the hot air inside and wicking it away outside. Spraying water will bring down the temperature of the air outside and helps increase efficiency. However; when you're dealing with 50 degrees+ C the water will eventually evaporate quickly, and you'll need to stop frequently to keep up the benefits which is counter-productive.

Posted by: @pranavesh-chander

What is the actual logic behind that? Does it make it any better in real? 

 

The logic might be trying to cool down the air next to the condenser. Theoretically, it can help but I'm not sure if that actually does make any difference in real life. 

The logic seems to make sense, but it's probably more of a waste of water than anything. The condenser coils are quite hot, the compressor on the engine pressurizes the refrigerant to the point where it becomes a hot liquid, that then flows through the condenser, so it can cool down via air flowing in through the grille. Water has a much higher heat capacity than air, meaning it takes a ton more energy to heat up a fixed weight of water to a temperature than that same quantity of air. That means it will cool the refrigerant in the condenser much quicker than blowing air will. The hot condenser's around 80 degrees C, which isn't really all that far from boiling. It'll steam like the faucet when you do the dishes. This, the running fan and the fact the condenser is vertical means water won't stay there for much longer than the time you're spraying it. Any cooling capacity boost is temporary at best.

As noted by others, spraying water on the condenser will increase efficiency due to evaporative cooling. However it is impractical, you'd need to have a mechanism to continuously spray the water and it would take an awful lot of it if driving any kind of distance. It would be better to make sure your AC is at peak efficiency with the condenser clear of debris and fins straight, plus condenser fan working properly for maximum airflow. It is also important to have the correct refrigerant charge. That car is old enough that some refrigerant may have leaked out, so to insure your AC system has the proper amount it would need to be leak-tested and leaks fixed if needed. Knowing you have the correct amount of refrigerant requires that the system be evacuated and recharged. Modern AC systems using variable-displacement compressors require a precise amount of refrigerant. A few ounces either way can noticeably affect performance.