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MRCOOL / DIY 5th Generation

PC 11 error code

Outdoor main control board DC bus high voltage protection from the voltage detection circuit.

Severity
technician
Verified
Jul 18, 2026

What triggers it

Outdoor main control board DC bus high voltage protection from the voltage detection circuit.

What to do

  1. Check the power supply; if it is not working, turn off the unit.
  2. Check power-supply connections and wires; correct connections or replace wires if needed.
  3. Power on and measure P-N voltage where applicable.
  4. Replace the IPM board if P-N voltage is abnormal.
  5. Check the reactor; replace the reactor if it is not normal, otherwise replace the outdoor 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

Technician-tier outdoor auxiliary board diagnostic; see service manual section 4.3

Source

MRCOOL R454B DIY-5 service manual
Document
data/sources/mrcool-diy5-service.pdf
Section
4.3 Error Display; 4.7 TS10-S
Page
37, 71
Verified Jul 2026

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