Mitsubishi Electric PUHY-HP120TNU-A, Service Handbook

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[7-4 Error Code Definitions and Solutions: Codes [2000 - 2999] ]
HWE18240_GB chapter 7 -
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7-4-4 Error Code [2502] (Models with a float switch)
1. Error code definition
Drain pump fault
2. Error definition and error detection method
1) The immersion of sensor tip in water is detected by the ON/OFF signal from the float switch.
Submergence of the sensor
When it is detected that the float switch has been ON for 15 seconds, it is interpreted that the sensor tip is immersed in
water.
Sensor in the air
When it is detected that the float switch has been OFF for 15 seconds, it is interpreted that the sensor tip is not immersed
in water.
2) If it is detected that the float switch has been ON for 3 minutes after the immersion of the sensor tip was detected, this is con-
sidered a drain pump failure, and "2502" appears on the monitor.
The total time it takes for this error to be detected is 3 minutes and 15 seconds, including the time it takes for the first im-
mersion of the sensor tip to be detected.
3) Detection of drain pump failure is performed while the unit is stopped.
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.
It is detected by the float switch that the sensor tip has been immersed in water for 15 minutes or more.
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
mechanism
(2) Drain water drainage problem
Œ
Clogged drain pump
Œ
Clogged drain piping
Check for proper drainage.
(3) Stuck float switch
Check for slime in the moving parts of the float switch. Check for normal operation of the float switch.
(4) Float switch failure Check the resistance with the float switch turned
on and turned off.
(5) Indoor unit control board failure
Œ
Drain pump drive circuit failure
Œ
Float switch input circuit failure
Replace indoor unit control board.
(6) 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 in-
door unit controller board.
(7) Items (1) through (5) above and an indoor unit electronic
valve closure failure (leaky valve) occurred simultane-
ously. Check the solenoid valves on the indoor unit for
leaks.