It may be a possibility that your output port 3 is damaged. It can happen by drawing too much current from a port. LEDs should always be used with at least a 220 Ohm or greater resistor. You should avoid using it directly to a port. This could cause a port to burn out. Depending on the type and color of an LED the resistance can vary a bit. I typically try to use at least a 1K Ohm resistor to be safe. We may want to try some other experiments to test if your port is working correctly or not.
As for the TMP36, make sure you have the +5V and GND connections correct. With the TMP36 "flat-side" facing you, the power +5V should be on the left pin-1, the middle pin-2 is always the signal going to the analog input on the Arduino, the ground GND should be on the right pin-3.