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Mitsubishi Electric Air Conditioner Pb Error Code

Indoor fan motor error. Here is what it means and how to clear it, easiest fix first.

Pb
May need a pro

The indoor unit's fan motor isn't running correctly. A failed motor, a wiring fault or something obstructing the blower wheel can cause it.

These check codes appear on wired wall controllers, mainly with P-series, Mr. Slim and ducted or ceiling units; wall-mounted M-series units (MSZ) usually report faults by blinking the OPERATION light instead. The meanings here come from Mitsubishi Electric's Mr. Slim code list for Singapore models, and they can differ by series and region, so check your manual.

Safety first: unplug the air conditioner (or switch off its breaker) before touching filters, hoses or panels. If you smell burning or gas, or see water near the outlet, stop and call a professional.

How to fix Mitsubishi Electric Pb

  1. Clean the filters

    Switch off the breaker, then remove and wash the indoor filters, let them dry and refit them. Don't reach into the air outlet or take covers off to get at the fan.

  2. Reset the power at the breaker

    Switch off the breaker that feeds the air conditioner (some systems have separate breakers for the indoor and outdoor units, so switch off both). Wait about five minutes, switch the power back on and restart the unit to see if the code clears.

When to call a technician

If the code returns, the fan motor or its circuit needs a technician.

Parts that commonly cause Pb

Order parts by your exact model number so they fit.

Other Mitsubishi Electric air conditioner codes

Frequently asked questions

What does Pb mean on a Mitsubishi Electric air conditioner?

The indoor unit's fan motor isn't running correctly. A failed motor, a wiring fault or something obstructing the blower wheel can cause it.

Can I fix Mitsubishi Electric Pb myself?

Only the basic checks. You can safely try the steps above, but Pb usually points to a part or fault that needs a technician.

What if Pb keeps coming back?

A code that returns after a reset and the checks above usually means a part is wearing out. Note when Pb appears (which cycle, how often) and have your model number ready; it helps a technician bring the right part on the first visit.

Last reviewed 2026-10-19. Codes and steps can vary by model; check your owner's manual.

References