I live in Tucson, AZ where the summer temps often exceed 100 degrees F. I have an 1991 300 SL which has an excellent A/C system (you could freeze meat in my car!) including 2 aux fans set to turn on automatically at slow or fast speed depending on the coolant temperature. This system works as designed. However, I made two very minor INEXPENSIVE upgrades that are relatively easy: 1) Replace the radiator cap ($6 at Pep Boys, etc.). On my car, it's a 20 lb cap which means that as the pressure builds up to anything below 20#, the coolant doesn't boil or escape out the overflow causing the car to overheat. (If any car repeatedly overheats, the head will warp requiring a very expensive repair). So a new $6 cap may keep the car from overheating. 2) My car (like most older cars) has an unused cigarette lighter and ashtray in the center console. If you remove the ash tray, that space will hold a large foam cup of water, etc. saving you the cost of buying a dumb looking add-on cup holder. If you unplug the the wires from the back of the lighter element and remove the element and go to ACE Hardware and buy a push switch ($5) that fits into the element. Drill out the element and install the push switch where the lighter previously went. Nothing is visible; No holes or weird switches in the dash, etc. I included 2 inline fuses wiring everything so that the fans still will come on automatically as designed. BUT, push the switch bypassing the automatic system turning the aux fans on high at any time. Push the switch again and the system reverts back to the automatic system. Everything shuts off when the ignition is off. The advantage is that I can turn the fans on earlier than the auto system or I can keep them on longer helping the cooling system operate at max even if in slow traffic on a blistering hot day.