Piper 19,
Yes the flight would be delayed if the brake temps are above 300 degrees with fans off or not fitted and 150 degrees if the fans are on (This is due to the brilliant design of the brake fans blowing directly onto the thermocouples! Designed by Porsche, built by Renault!)
This is a pre takeoff requirement and has bitten me a couple of times whilst on short turnrounds with short runways and a c**p old airbus with no brake fans.