An A/C compressor will probably put a noticeable strain on a 216- - - - -they're a bit underpowered already. Also, figuring out a way to drive the compressor might be a challenge, as most 216's only have single-groove crankshaft pulleys. There is a way to mount a compressor near an alternator and use a 2-groove pulley on the alternator to drive the compressor, but it requires some pretty creative mounting bracket fabrication for the compressor. Very dry desert climates are ideal for swamp cooler operation, as they rely on evaporation of the water that circulates over the packing to cool the air. Your climate is about the ONLY place a swamp cooler does much good- - - - -here in Tennessee one just blows a lot of hot, wet air!
Jerry
