Mitsubishi Electric PUMY-P36NKMU3 Technical & Service Manual page 61

Check code
1501
(U2)
Abnormal points and detection methods
If stop valve is closed during cooling operation.
When both of the following temperature conditions have been satisfied for
20 minutes or more during cooling operation.
1. TH22j − TH21j ] −3.6°F [−2°C]
2. TH23j − TH21j ] −3.6°F [−2°C]
Note:
For indoor unit, the abnormality is detected if an operating unit satisfies the
condition.
●Diagnosis of defects
Make sure to turn the power OFF before connecting/disconnecting any connectors, or replacing boards.
Is the outdoor stop valve
(liquid/gas) fully open?
Disconnect the outdoor LEV wiring to
check the resistance.
Is the resistance detected?
OCH733
Closed valve in cooling mode
Diagnosis
No
Yes
No
Yes
v
Causes and checkpoints
Outdoor liquid/gas valve is closed.
Mulfunction of outdoor LEV (LEV-A) (blockage)
TH21: Indoor intake temperature thermistor
TH22: Indoor liquid pipe temperature thermistor
LEV: Linear expansion valve
Open the outdoor stop valve
(liquid/gas) fully.
Replace the outdoor LEV.
Replace the outdoor controller board.
61
Remedy