Toshiba MMU-AP0151MH P19 Way valve operation error, P20 High-pressure protective operation

Check code name Check code name Cause of operation

[P19]	4-way valve operation error	1.	4-way valve error
		2.	TS1 sensor/TE1 sensor error
		3.	Pd sensor/Ps sensor error
		4.	TE sensor/TL sensor misconnection

Check code name Check code name Cause of operation

[P20]	High-pressure protective operation 1.	Pd sensor error
	2.	Service valve closed.
	3.	Indoor/outdoor fan error
	4.	Indoor/outdoor PMV clogging
	5.	Indoor/outdoor heat exchanger clogging
	6.	SV2 circuit error

Auxiliary code : Detected outdoor unit No.

Is 4-way valve coil		NO
connector connected?
	YES

Correct connector connection.

(4-way valve coil: CN317)

Correct connector connection.

7.	SV4 circuit error
8.	SV5 circuit error
9.	Outdoor I/F P.C. board error
10.	Operation error of check valve of main
	discharge pipe
11.	Refrigerant overcharge

Are TS1, TE1, Pd, Ps sensor		NO
connectors connected?
	YES
		NO
Are characteristics of resistance value
of TS1 and TE1 sensors normal?
	YES
		NO
Are output voltage characteristics
of Pd and Ps sensors normal?
86	YES
		NO
Are connection and installation
of TE1 and TL sensors correct?

TS1 sensor: CN504

TE1 sensor: CN505 Pd sensor: CN501 Ps sensor: CN500

Replace sensor.

Replace sensor.

Correct connection

and installation.

Are service valves fully opened?

YES

Are characteristics of

high-pressure sensor normal?

YES

Check mispiping of discharge gas/

suction gas main pipes.

Normal

Check operation of PMV3 SV12.

Normal

Is the flow selector unit normal?

Normal

Reset power supply, and start a test operation corresponded to the season.

NO

NO

Abnormal

Abnormal

Abnormal

All cooling operation	To	B
All heating operation	To	C

Open service valves fully.

Check parts.

Failure Replace

Correct piping.

Replace defective parts.

Repair the flow selector unit.

YES

B All cooling operation

1. Pressure by pressure gauge (Check joint)

2.	Pressure display on 7-segment display
3.	Output voltage of I/F P.C. board
	If 1 and 2, 3 are different, an error of pressure sensor is considered.

Reset the power supply and start heating test operation.

Does cooling outdoor fan normally operate?

YES

Is there no fan crack or coming-off?

If 2 and 3 are different, check I/F P.C. board.

NO

Correct faulty parts.

YES

Correct faulty parts.

Is the flow selector unit normal?

YES

Does 4-way valve operate?

NO

4-way valve error

NO

YES	Does not discharge		NO
	refrigerant gas bypass to
	suction side through
	4-way valve?	*1

YES

Check 4-way valve.

Replace the FS unit.

If an error did not occur in test operation, restart the operation.

NO

Is outdoor PMV1, 2 normal?

YES

Is there a cause to interfere operation of heat exchanger of outdoor unit?

1.Heat exchanger clogging

2.Air short circuit

NO

Is SV2 circuit normal?

YES

Is SV4 circuit normal?

(Connector connection, fan IPDU, fan motor, wiring)

NO

Correct faulty position.

(Connector connection wiring, coil mounting, valve clogging, etc)

YES

Eliminate the interfered causes.

NO

Repair SV2 circuit.

(Coil error, clogging, disconnection of cable, etc.)

NO

Repair SV4 circuit.

*1 Check TS and TE temperature of the outdoor unit which compressors is operated.

(I/F) SW01=[1], SW02=[6], SW03=[2]	TS sensor temperature
SW01=[1], SW02=[7], SW03=[2]	ÆTE sensor temperature

<Judgment criteria>

TE sensor: Normal if TE ≤ 20˚C except summer season (Outside temp 20˚C or lower)

TS sensor: Normal if TS ≤ 40˚C except summer season (Outside temp 20˚C or lower)

YES

Does check valve of main

discharge pipe normally operate?

YES

Refrigerant overcharge, clogging, pipe breakage, abnormal overload condition

(Coil error, clogging, disconnection of cable, etc.)

NO

Repair check valve. Replace