Toshiba MMU-AP0091H service manual 148, Low oil level protection, Leakage check for SV3C valve

Check code Check code name Cause of operation

[H07] / [d7]	Low oil level protection	1. Valves of balance pipes closed.
(TCC-L / AI-NET)		2. Miscabling or misinstallation of TK1 to TK4 sensors
		3.	TK1 to TK4 sensor error
		4.	Gas leak or oil leak of all outdoor units
		5.	Refrigerant stagnation of compressor case
		6.	SV3A, 3B, 3D, 3C, 3E valve error
		7.	Clogging of oil return circuit from oil separator
		8.	Clogging of oil-equation circuit system

In some cases, it may be difficult to check for leakage or clogging of refrigerant in low ambient temperature condition. In this case, it may take longer for the system to warm up before commencing checks.

(Criteria: Discharge temperature of TD1 and TD2 are 60°C or higher)

(*1)

a) Leakage check for SV3A valve (for multiple outdoor unit system)

• Turn off the power supply, take off connector of SV3A valve, and then start a test operation after power-ON.

• Check the temperature change at secondary side of SV3A valve during operation

(1 in the figure on the next page).

• If temperature is increased, it is a leakage of SV3A valve.

Replace SV3A valve.

Are TK1, TK2, TK3, and

TK4 sensors connected correctly?

Is sensor fitted correctly or mis-installed.

YES

Are TK1 and TK2 sensors connected correctly?

Is sensor fitted correctly or mis-installed.

Are sensor characteristics normal?

YES

Check leakage of SV6 circuit.

Normal

NO	Correct miswiring.
	( TK1: CN514, TK2: CN515 )
*
	TK3: CN516, TK4: CN523
NO
	Correct miswiring.
	(TS1: CN504, TS2: CN522)
Characteristics-2	Sensor error ÆReplace

Abnormal

Replace defective parts.

b) Leakage check for SV3C valve

• Turn off the power supply, take off connector of SV3C valve, and then start a test operation after power-ON.

• After operation for several minutes, check temperature at secondary side of SV3C valve

(2 in the figure on the next page).

• If temperature is high (equivalent to discharge temperature TD), it is a leakage of SV3C valve.

Replace SV3C valve.

(Even if there is leakage from SV3C valve does not occur, temperature of SV3C valve at secondary side

rises during operation. When the checked temperature is equivalent to TD temperature, it is a leakage of

SV3C valve. Replace SV3C valve.)

c) Clogging check for SV3B valve (for multiple outdoor unit system)

148

Check setup of cooling only		Abnormal	Set up cooling only operation mode.
			Item code (DN) OF
indoor units is correct.
			Cooling only operation mode: 0001
	Normal	NO
Are characteristics of TK1 to TK4 normal?
			Sensor error ÆReplace

*Characteristics-4

		YES
Check gas leak of outdoor unit.					Abnormal		Determine position where
								gas leaked and repair.
(Check oil leak at the outdoor unit.)								(Recharge, refill oil.)
		Normal
					NO
Is the flow selector unit normal?							Repair the flow selector unit.
	YES
Check accumulation of			NO		(*1) Check leakage of		YES
					solenoid valve. (SV3C)				Replace defective parts
refrigerant in compressor case.					Check clogging.
	Refrigerant accumulation				(SV3E)
						No leakage or clogging
Correct accumulation of
refrigerant in compressor case,
resetstartpoweroperation.supply and					(*2) Check clogging in oil		YES
					recovery circuit of the oil separator.				Replace defective parts
					(Capillary, Strainer)
					Check clogging of SV3D valve.
Check oil level judgment						No clogging
of each compressor.
		SW01/02/03=1/16/1		are
		displayed on 7-		segment display.
Are all the oil levels appropriate?
			NO
	YES						Clogging
					Check clogging of
Eliminate cause of stagnation.					oil-equalization circuit.				Replace defective parts
					(*3)

Indoor/outdoor PMV error (Cause of refrigerant stagnation) Discharge check valve error, etc.

•	While outdoor unit is operating, set up SW01/02/03 = [2] [1] [3] to 7-segment display [Hr], and push SW04
	for 2 seconds or more, [Hr] [2] is displayed.
•	Set up SW02 = [9], and turn on SV3A, SV3B, SV3C valves (7-segment display [Hr] [ 3-]).
•	While outdoor unit is operating, check temperature change at secondary side of SV3B valve
	(3 in the figure on the next page).
	• If temperature does not rise (equivalent to suction temperature), it is a clogging of SV3B valve.
	Replace SV3B valve.
d) Clogging check for SV3E valve
•	While the outdoor unit is operating, set up SW01/02/03 = [2] [1] [3] the 7-segment display A displays [Hr],
	and push SW04 for 2 seconds or more, [Hr] [ 2] is displayed.
•	Set up SW02 = [10], and turn on SV3E valve (7-segment displays [Hr] [ ]).
•	After operating for several minutes, check the pipe temperature at the secondary side of the SV3E valve.
	If it is the equivalent to the outside temperature, SV3E valve may be clogged.
	Replace SV3E valve.
• Note: If SV3E valve is clogged, the temperature of all TK1 to TK4 sensors do not change.

(*2) Clogging check for SV3D valve of oil return circuit from oil separator

a)Oil return circuit

•While outdoor unit is operating, check temperature (secondary side of capillary) on oil return circuit (5 in the figure on the next page).

If temperature is equivalent to suction temperature, a clogging of strainer of oil return circuit or capillary is considered.

Repair the clogged part.

b)Clogging check for SV3D valve

•While outdoor unit is operating, set up SW01/02/03 = [2] [1] [3] to 7-segment display [Hr], and push SW04 for 2 seconds or more, [Hr] [2] is displayed.

•Set up SW02 = [7], and turn on SV3D valve (7-segment display [Hr] [ 3d]).

•If temperature is low at secondary side of the valve or it does not change, clogging of valve, capillary, or strainer is considered ( 6 in the figure on the next page).

(Note) When refrigerant stagnates in compressor shell, there may appear to be a low oil level.