88 5ktq Rad Fan Stage 1

["Mike Hopton" <mike@genesis-microchip.on.ca>]

     The radiator fan on my '88 5ktq runs all the time when the climate 
     control is switched on (independent of the setting e.g. Bi, Screen, 
     Auto etc). This happens even when the engine is cold, doesn't seem 
     right to make sense to me, is it supposed to do this? 
     
     If I turn the climate control off, then the radiator fan switches off 
     (engine cold). Does the temp switch at bottom left hand side of the 
     rad control the stage 1 speed, if not which of the myriad of sensors 
     does? It's definitely stage 1 'cause when I pull the relay the fan 
     stops.
     
     Thanks and regards, Mike