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Error code reference

Mitsubishi Air Conditioner Error Code PS

PU stop

Mitsubishi codesMitsubishi air conditioner codes

PU stop - motor stopped using STOP/RESET under mode other than PU operation mode.

First step from the service manual

Check for stop made by pressing STOP/RESET; turn start signal OFF and release with PU/EXT.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What PS means on a Mitsubishi air conditioner

The PS error code on a Mitsubishi air conditioner indicates a PU Stop condition. This occurs when the STOP/RESET button is pressed while the unit is operating in a mode other than PU (Panel Unit) operation mode. In systems configured for EXT (external signal) or combined PU/EXT operation modes, pressing STOP/RESET generates a conflict because the stop command originates from the panel rather than through the expected control channel. The drive registers this as an abnormal stop condition and displays PS to flag the operational mismatch.

This is not a hardware fault in the traditional sense. No motor winding failure, inverter fault, or sensor malfunction is involved. Instead, PS is a control logic flag indicating that the stop sequence was initiated through an incompatible input method for the currently active operating mode. The motor is halted as a protective response to this conflicting command, and the system will not resume normal operation until the conflict is resolved through the correct sequence.

To clear the PS condition, the technician must first confirm that the STOP/RESET button was the trigger. The start signal must then be turned OFF, and the operating mode must be switched to PU or the PU/EXT combined mode before issuing a release command. Simply cycling power without resolving the mode conflict will not produce a lasting fix. The correct recovery procedure requires switching the mode selector appropriately and then releasing the fault through the PU/EXT setting.

Source: manufacturer service documentation.

Common causes of PS

  1. 01

    STOP/RESET pressed in wrong operating mode

    Wiring / connection

    The most direct cause of PS is pressing the STOP/RESET button while the unit is in EXT or a non-PU mode. The control logic flags this as an invalid stop source and halts the motor.

  2. 02

    Incorrect mode configuration after wiring changes

    Wiring / connection

    If external control wiring was recently modified or reconnected, the operating mode may have been left in EXT mode. A panel-initiated stop in this state will trigger PS.

  3. 03

    Accidental button press during commissioning

    Wiring / connection

    During initial setup or test runs, technicians may inadvertently press STOP/RESET before confirming the active operating mode, generating the PS condition unexpectedly.

  4. 04

    Start signal not properly turned OFF before reset attempt

    Wiring / connection

    If the external start signal remains active when attempting to clear the fault, the system cannot process the release correctly. The start signal must be turned OFF as part of the recovery sequence.

  5. 05

    Mode selector switch fault or misreading

    Part replacement

    In rare cases, a faulty or dirty mode selector switch may cause the drive to interpret the active mode incorrectly, leading to repeated PS faults even when the correct mode appears to be selected.

See the test procedure for each cause

Frequently asked questions about PS

What does PS mean on a Mitsubishi air_conditioner?
PS stands for PU Stop and indicates that the STOP/RESET button was pressed while the unit was operating in a mode other than PU operation mode. This creates a control conflict because the stop command came from an incompatible input source for the active mode. The unit halts the motor and displays PS until the condition is properly cleared. It is a control logic flag, not a component failure.
How do I fix the PS error on my Mitsubishi air conditioner?
To clear the PS error, first turn the external start signal OFF. Then switch the operating mode to PU or PU/EXT as appropriate for your installation. Once the correct mode is active, use the PU/EXT setting to release the fault and resume operation. Do not attempt to restart without addressing the mode conflict, as the fault will likely return.
Will resetting the power clear the PS error code?
A simple power cycle may temporarily clear the PS display, but if the underlying mode conflict is not resolved, the error will return as soon as the unit is operated and the STOP/RESET button is pressed again in the wrong mode. The correct procedure requires turning the start signal OFF and releasing the fault through the proper PU/EXT mode selection.
Is the PS error on a Mitsubishi air conditioner a safety concern?
The PS error itself does not indicate a dangerous electrical or mechanical failure. The unit stops the motor as a controlled response to a conflicting control input, which is a normal protective behavior. However, the system will remain non-operational until cleared, so addressing it promptly is important for comfort and system health.
How much does it cost to fix a PS error on a Mitsubishi air conditioner?
In most cases, the PS error requires no replacement parts and involves only a procedural correction to the operating mode and control signals. If a service technician is called to diagnose and clear the fault, you can expect a standard diagnostic service call fee, typically in the range of $75 to $150 depending on your region. If a faulty mode selector component is identified, parts and labor costs would be additional.

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