you mean that your clutch fan never engaged when hot? - it maybe a dead fan clutch, if you bought it used then its best to overhaul it before putting it on the engine, the fluid is available at toyota spare shops in Karachi - the 3000 cst fluid costs about Rs 700/bottle,
The clutch's activtating piston has a bimetal spring element on top of it, which if it is plugged with dirt - it wll never let the fan engage, And if someone has messed with the position of the spring then it may engage too early or too late. And to top it - the fan clutch requires blazing hot air from the radiator to twist the bimetal spring, If your shroud is not good or you have poor airflow through the radiator or have blocked radiator lines right infront of the clutch - it will not engage.
But when it does engage nothing can match the colossal airflow of an engine driven clutch fan. When running with A/C its best to use a nominal sized condenser fan (ideally tripped by a pressure switch) to help the clutch fan when at a standstill. The pressure switch should shut off the fan when the headpressure gets into tolerable range (meaning the clutched fan or movement of the car is doing all the required airflow work)