Symbol 3398 from ISO 7000 - Title/Meaning: Temperature, low Function/description: To identify the low temperature position of a control. To indicate that the temperature is at a low level.
pay attention to orientation of symbolAdditional information: 
Colour may be blue to signify cool or cold temperatures.
Own work using: iso.org/obp/graphics/grs/84b029d5-7c7e-4497-acf0-c3d5a359c28f 200.png
Vectorization:  Mrmw