Here is info if you do decide to replace the outside temp sensor. LH temp sensor for ECM. RH temp sensor for Climate and DIM display of the outside temp.
The mirror temp sensor is the round bump on the bottom side of the mirror, #6 in parts pic. The YouTube video shows how to remove the mirror and door panel. Ignore the mirror motor replacement. You are replacing the temp sensor and white pig tail temp wires that goes into the green connector. It does not matter which temp wire goes back into the correct connector hole of the green connector.
(683) Volvo S60 Door Mirror Disassembly and Replacement - (S60, S80, V70, XC70) - YouTube
View attachment 178223
6 Sensor, L.H., temperature sensor, left 1.00 31104009
Sensor, L.H., temperature sensor, left 1.00 30634727
Sensor, R.H., temperature sensor, right 1.00 31104010
Sensor, R.H., temperature sensor, right 1.00 30634728
Outside temperature sensor
The outside temperature sensor detects the temperature in the surrounding air. The signal is used by the engine control module (ECM) as a substitute value in the event of a fault in certain components or functions and to control certain diagnostic functions.
The sensor is a negative temperature coefficient (NTC) type which is supplied with power from the control module (signal) and is grounded in the control module.
The resistance in the sensor, which provides a signal between 0-5 V, changes depending on the outside temperature. Low temperatures produce high voltage (high resistance), high temperatures produce low voltage (low resistance).
The outside temperature sensor is positioned in the left door mirror.
The engine control module (ECM) can diagnose the outside temperature sensor. The sensor value can be read off using VIDA.