I'm about a week away from upgrading my a/c on my car. I know there is a temp switch for the fan on top of the drier and a pressure switch near the liquid line from the condenser to turn the compressor off for too high or too low of pressure. I currently have a relay rigged up to turn on the aux fan whenever the compressor is called for. But it is silly to have that 20 amp load when im on the highway... is there a dual use pressure switch or lower temp Switch to kick the aux fan on at a lower temp/ pressure? I don't like the factory setup where it waits until the last minute and my head pressure is like 350psi haha!

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83 300CD- sanden, dual p/f condensers, 160a alternator, ect
91 300TD- 722.6, #22 head, 3.5L IP, w140 manifolds, ect