Blocked Valve In Cooling Mode - Mitsubishi Electric MXZ-4C36NAHZ Service Manual

Check code
1501
Abnormal points and detection methods
Abnormal if stop valve is blocked during cooling operation.
Abnormal when both of the following temperature conditions are satisfied
for 20 minutes or more during cooling operation.
1. TH22j − TH21j ] 28.4°F [−2°C]
2. TH23j − TH21j ] 28.4°F [−2°C]
Note:
For indoor unit, the abnormality is detected if an operating unit satisfies the
condition.
●Diagnosis of defectives
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 there a resistance detected?
OCH573

Blocked valve in cooling mode

Diagnosis
No
Yes
No
Yes
v
Causes and check points
Outdoor liquid/gas valve is blocked.
Mulfunction of outdoor LEV (LEV-A) (blockage)
TH21: Indoor intake temperature thermistor (RT11 or TH1)
TH22: Indoor liquid pipe temperature thermistor (RT13 or TH2)
TH23: Branch box gas pipe temperature thermistor (TH-A to E)
LEV: Electronic expansion valve
Open the outdoor stop valve
Replace the outdoor LEV.
Replace the outdoor controller board.
51
Remedy
(liquid/gas) fully.