MRCOOL / DIY 5th Generation
PC 0A error code
High condenser/outdoor pipe temperature protection.
- Severity
- technician
- Verified
- Jul 18, 2026
What triggers it
High condenser/outdoor pipe temperature protection.
What to do
- Check whether condenser temperature is above the manual threshold.
- Check whether outdoor ambient temperature is above the manual's outdoor-temperature limit; stop the unit if it is.
- Check outdoor ventilation, outdoor fan operation, dirty heat exchanger, refrigerant level, and refrigerant system.
- Check the outdoor pipe temperature sensor-to-PCB connection; correct the connection if needed.
- Measure the sensor resistance; replace the sensor if the value is abnormal, otherwise replace the outdoor main PCB.
Whether it self-clears
The unit starts again only when outdoor pipe temperature is less than 125.6F (52C).
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
Technician-tier outdoor auxiliary board diagnostic; see service manual section 4.3
Source
- Document
- data/sources/mrcool-diy5-service.pdf
- Section
- 4.7 TS27-INV: High temperature protection of condenser diagnosis and solution
- Page
- 77