MRCOOL / DIY 5th Generation
EH C3 error code
The indoor unit receives a refrigerant sensor fault signal for 10 seconds or does not receive refrigerant sensor feedback for 150 seconds.
- Severity
- technician
- Verified
- Jul 18, 2026
What triggers it
The indoor unit receives a refrigerant sensor fault signal for 10 seconds or does not receive refrigerant sensor feedback for 150 seconds.
What to do
- Check the connection between the refrigerant sensor and the indoor PCB.
- Correct the wiring if the refrigerant sensor is not properly connected.
- Replace the refrigerant sensor.
- If the fault still exists after replacing the sensor, replace the indoor main PCB.
Which systems show it
- MRCOOL DIY 5th Generation single-zone 9k, 12k, 18k, 24k, and 36k D25 indoor/outdoor models listed in manual section 1.1.
Related codes
Technician scope
Refrigerant sensor, PCB
Source
- Document
- data/sources/mrcool-diy5-service.pdf
- Section
- 4.7 TS05-N10: Refrigerant sensor error diagnosis and solution
- Page
- 68