Mitsubishi Electric PURY-HP144, Service Handbook

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[7-4 Error Code Definitions and Solutions: Codes [2000 - 2999] ]
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7-4-3 Error Code [2502] (Models with a drain sensor)
1. Error code definition
Drain pump fault
2. Error definition and error detection method
1) Make the drain sensor thermistor self-heat by passing current through it. If the temperature rise is small, it is interpreted that
the sensor is immersed in water. This condition is considered to be a preliminary error, and the unit goes into the 3-minute
restart delay mode.
2) If another episode of the above condition is detected during the preliminary error, this is considered a drain pump error, and
"2502" appears on the monitor.
3) This error is always detected while the drain pump is in operation.
4) The following criteria are met when the criteria for the forced stoppage of outdoor unit (system stoppage) are met.
"Liquid pipe temperature-inlet temperature
”
-10°C [-18°F]" has been detected for 30 minutes.
The immersion of drain sensor is detected 10 consecutive times.
The conditions that are listed under items 1) through 3) above are always met before the criteria for the forced stoppage
of the outdoor unit.
5) The indoor unit that detected the conditions that are listed in item 4) above brings the outdoor unit in the same refrigerant
circuit to an error stop (compressor operation prohibited), and the outdoor unit brings all the indoor units in the same refrigerant
circuit that are in any mode other than Fan or Stop to an error stop. "2502" appears on the monitor of the units that came to
an error stop.
6) Forced stoppage of the outdoor unit
Detection timing: The error is detected whether the unit is in operation or stopped.
7) Ending criteria for the forced stoppage of outdoor unit
Power reset the indoor unit that was identified as the error source and the outdoor unit that is connected to the same refrig-
erant circuit.
Forced stoppage of the outdoor unit cannot be cancelled by stopping the unit via the remote controller.
(Note) Items 1) - 3) and 4) - 7) are detected independently from each other.
The address and attribute that appear on the remote controller are those of the indoor unit (or OA processing unit)
that caused the error.
3. Cause, check method and remedy
Cause Check method and remedy
(1) Drain pump failure Check for proper functioning of the drain pump.
(2) Drain water drainage problem
Œ
Clogged drain pump
Œ
Clogged drain piping
Check for proper drainage.
(3) Adhesion of water drops to the drain sensor
Œ
Trickling of water along the lead wire
Œ
Rippling of drain water caused by filter clogging
1) Check for proper lead wire installation.
2) Check for clogged filter.
(4) Indoor unit control board failure
Œ
Drain pump drive circuit failure
Œ
Drain heater output circuit failure
If the above item checks out OK, replace the indoor unit
control board.
(5) Wrong dipswitch setting on the indoor unit controller
board
Œ
Dipswitch for the new indoor unit controller board
was wrongly set to "unit model without drain
pump" instead of "unit model with drain pump"
when the board was replaced.
Check for proper dipswitch model setting on the indoor unit
controller board.
(6) Items (1) through (4) above and an indoor unit elec-
tronic valve closure failure (leaky valve) occurred si-
multaneously. Check the solenoid valves on the indoor unit for leaks.