ACiQ EH61

What does ACiQ EH61 mean?

EH61 indicates an indoor unit pipe temperature sensor (T2) error. The T2 sensor reads the indoor coil pipe temperature used by the control logic. The error is flagged when the sensor's sampling voltage is outside its valid range, indicating an open or short circuit in the T2 sensor or its wiring.

Symptoms

• EH61 shown on the indoor unit display
• Improper cooling, heating, or defrost behavior
• Unit may stop or run abnormally
• Fault isolated to the indoor coil-pipe sensor circuit

Common causes

• Open or short circuit in the T2 sensor
• Loose or damaged sensor wiring or connector
• Out-of-range sensor resistance value
• Faulty indoor PCB sensor input

Diagnostic steps

1. 01

   Inspect the sensor connection

   Check the wiring between the pipe temperature sensor and the indoor PCB and ensure it is properly connected.

2. 02

   Measure the sensor resistance

   Measure the T2 sensor's resistance and compare it against the manual's resistance table; replace it if out of range.

3. 03

   Reseat or repair wiring

   Correct any loose or damaged connection found at the sensor or board.

4. 04

   Replace the indoor PCB if needed

   If the sensor and wiring are good, the indoor board sensor input is the next likely cause.

When to call a professional

Confirming a coil-pipe sensor fault with a meter and replacing the sensor or indoor board requires opening the indoor unit and working with electronics that can hold a charge after power-off. If EH61 remains after a basic connection check, contact a licensed HVAC technician. Resistance testing against the manufacturer's table and board-level replacement should be carried out only by a qualified service professional.