Turn ON Motor DC if temperature Reach 30°

Using Arduino Project Guidance
1

I want to make a program where if the temperature reach 30° a DC motor turns on for 5 sec and then even If the temperature keeps at 30° that the motor dont turn on again.
the problem with the programI have is that if the temperature is at 30° the motor turns on for 5 sec but if the temperature keeps 30° the motor keeps turned On

2

Sorry, but my crystal ball has crashed again and my mind-reading powers aren't working, so I cannot see your code.
Post your code here, between code tags (the "</>" button above the posting window) so that we can see where you are going wrong.

3

Add a flag variable that is set when the motor is turned on.

test to see if it has been set before turning motor on.

bool motorHasRun = false;         // flag variable

void setup() { }

void loop() {
if (temp > tempThreshold && motorHasRun == false){           // test temp and flag
  digitalWrite (motor,HIGH);     // example motor run code
  motorHasRun = true;            // set flag so motor can't run more than once             
 }
}

if you need to reset it so the motor can run again you can do something like:

if (temp < tempThreshold){   // some condition that that will trigger reset
 motorHasRun = false;                 // reset flag
 }