temperature controlled fan

about the light post circuit for the project may i knw wthat is the uses of spdt switchin the schematic and we have 4 switch in the schematic 1 for reset,1 for 3 for high medium low, and 1 more is for atomatic or manual is it?and the 7 segment display should display 4 digit like 23.33 or 3 digit,1 for unit like 23.3'C

It depends on you how you want to use the switches or display. regarding the reason why SPDT switch is used.. Please consult Y. S. Yong who actually made the circuit.. he can only tell you why he used.

Regarding seven segment, it actually depends on you how you want to use... you can either use it as 2 digit display with °C display or 3 digit display with one decimal precision.