Overheat Protection; Compressor Overcurrent Interruption; Low Pressure(Rp200); Compressor Current Sensor Error Or Input Current Error - Mitsubishi Electric PUHZ-RP250YHA2 Service Manual

Abnormal point and detection method
Error Code
Abnormality such as overvoltage or
voltage shortage and abnormal
synchronous signal to main circuit
Abnormal if any of followings are detected
during compressor operation;
• Instantaneous decrease of DC bus volt-
age to 400V
U9
• Increase of DC bus voltage to 760V
(4220)
• Decrease of input current of outdoor unit
to 0.5A only if operation frequency is
more than or equal to 40Hz or compres-
sor current is more than or equal to 5A.

Overheat protection

Abnormal if outdoor pipe thermistor (TH3)
detects 70 or more during compressor
Ud
operation.
(1504)

Compressor overcurrent interruption

(When compressor locked)
Abnormal if overcurrent of DC bus or
compressor is detected within 30 seconds
after compressor starts operating.
UF
(4100)
Compressor current sensor error or
input current error
Abnormal if compressor current sensor
UH
detects –1.0A to 1.0A within 3 minutes
(5300)
after compressor starts operating. (This
error is ignored in case of test run mode.)

Low pressure(RP200)

Abnormal if the following conditions are
detected for continuously 1-3 minutes after
compressor starts heating operation for 5
minutes.
1. Heating mode
Detection mode1
TH7-TH3 4 and
TH5-Indoor room temperature 2
Detection mode2
TH7-TH3 2
TH5-Indoor room temperature 4
UL
TH2-Indoor room temperature 4
(1300)
2.Cooling mode
TH6-TH7 2 and
TH3-TH7 2
Indoor room temperature - Indoor liquid
pipe temperature (TH2) 5
Thermistor
TH3 : Outdoor liquid pipe temperature
TH5 : Indoor cond./eva. temperature
TH6 : Outdoor 2-phase pipe temperature
TH7 : Outdoor temperature
Decrease of power supply voltage
Disconnection of compressor
wiring
Defective 52C drive circuit of
outdoor power circuit board
Disconnection or loose con-
nection of CN5 on the outdoor
power circuit board
Disconnection or loose con-
nection of CN2 on the outdoor
power circuit board
Defective outdoor controller cir-
cuit board
Defective outdoor fan (fan
motor) or short cycle of outdoor
unit during cooling operation
Defective outdoor pipe ther-
mistor (TH3)
Defective outdoor controller board
Stop valve is closed.
Decrease of power supply voltage
Looseness, disconnection or
converse of compressor wiring
connection
Defective compressor
Defective outdoor power board
Dip switch setting difference of
outdoor controller circuit board
Disconnection of compressor
wiring
Defective circuit of current
sensor on outdoor power
circuit board
Stop valve of outdoor unit is
closed during operation.
Leakage or shortage of refrigerant
Malfunction of linear expansion
valve
Clogging with foreign objects in
refrigerant circuit
Clogging occurs in the parts
and which become below freez-
and ing point when water enters in
refrigerant circuit.
and
Case
Check the facility of power supply.
Correct the wiring (U·V·W phase) to compressor.
Refer to 10-9 (Outdoor power circuit board).
Replace outdoor power circuit board.
Check CN5 wiring on the outdoor power
circuit board. Refer to 10-9.
Check CN2 wiring on the outdoor power
circuit board. Refer to 10-9.
Replace outdoor controller circuit board.
Check outdoor unit air passage.
Turn the power off and on again to check
the error code. If U4 is displayed, follow the
U4 processing direction.
Open stop valve.
Check facility of power supply.
Correct the wiring (U·V·W phase) to
compressor.
Refer to 10-9 (Outdoor power circuit board).
Check compressor.
Refer to 10-6.
Replace outdoor power circuit board.
Check the dip switch setting of outdoor con-
troller circuit board.
Correct the wiring (U·V·W phase) to
compressor. Refer to 10-9 (Outdoor power
circuit board).
Replace outdoor power circuit board.
Check stop valve.
Check intake superheat.
Check leakage of refrigerant.
Check additional refrigerant.
Check linear expansion valve.
Refer to 10-7.
After recovering refrigerant, remove water
from entire refrigerant circuit under vacuum
more than 1 hour.
32
Judgment and action