Clutch cycling switch

The clutch cycling sw controls the minimum evap temp, to as stated, prevent evap freeze up. The low pressure sw (on the drier, if my memory is correct) will cut off the compressor, if the refrigerant is too low. This protects the compressor from failure due to lack of oil. If it were my vehicle, I would replace the low pressure switch with a dual low/high pressure switch, that will protect the system from high head pressure, due to lack of air flow thru the condenser.
PS: With the thermal clutch cycling sw, make sure you use "thermal grease", not silicon grease. Same stuff as used on the back of the GM ign modules