On engines with belt-driven cooling fans, a fan clutch is often used to save energy and reduce noise. The fan clutch disengages slows or disengages the engine's cooling fan when extra cooling isn't needed. The fan pulls air through the radiator and air conditioning condenser when the vehicle isn't moving fast enough to provide adequate airflow for cooling.
St Augustine grass will go dormant when the soil temperatures fall below 55 degrees. If the soil remains warmer than 60 degrees all year, the grass will stay green. It will, however, slow in growth as the soil drops in temperature. Disadvantages of St Augustine grass. One of the disadvantages of St Augustine grass is its poor wear tolerance.
PLANT WHEN DAYTIME TEMPERATURES ARE BETWEEN 60 & 75 DEGREES: Cool season grasses grow best when the soil temperatures are between 50 and 65 degrees F. These temperatures usually occur when the daytime air temperatures are between 60 and 75 degrees. High temperatures of summer can cause these plants to go dormant and thus planting during summer is asking for problems.