Would you mind telling me 'in dummy's guide format' (as my knowledge level obviously requires) the tests I need to perform to measure the voltages to get the voltages you suggested?
You take a multi meter set to volts.
Put the black wire on the ground.
Then put the red wire on the analogue connection into the arduino from the temperature sensor. Make a note of the reading. Now move the red wire to the light resistor and make a note of the reading.
Finally move the red wire back to the temperature sensor, look at the reading and then remove the analogue input from the light sensor.
Do you see a change in voltage like you see a change in the reading of the voltage from the arduino?