Bosch Outdoor Coil Temperature Sensor (T3) for IDS Heat Pumps

The Bosch Outdoor Coil Temperature Sensor (also called the T3 outdoor coil thermistor or coil temp sensor) is a genuine replacement part for Bosch IDS heat pump condensing units. It reads the temperature of the outdoor coil and sends that reading to the unit's control board.

Key Features:

• Coil temperature monitoring: The thermistor reads the outdoor coil temperature and reports it to the control board.
• Defrost control: In heating mode, the Demand Defrost Control uses the coil reading together with the outdoor ambient reading. It uses both to decide when to start and end a defrost cycle.
• Fan control: The reading is used for outdoor fan control in cooling mode.
• High and low temperature protection: The control board uses the reading to protect the compressor. It de-energizes the compressor at high coil temperatures and re-energizes it once the coil cools.
• OEM replacement: Built to Bosch specifications to match the original sensor.

A failed or out-of-range coil sensor can cause error codes, poor defrost operation, or compressor protection faults. Replacing it with a genuine Bosch sensor restores accurate readings and normal system control. The sensor is typically mounted on a U-bend of the outdoor coil, and it can be checked with a multimeter by measuring its resistance.