Toshiba HWS-1402XWHM3-E, HWS-802XWHT6-E, HWS-802H-E A04 Error Freeze prevention control

[A04] Error Freeze prevention control

When the outside temperature or inlet water temperature is low (approx. 20°C or lower) and the room load is large (operation frequency rating), the freeze prevention control may be activated.

Start

Operation restart

Perform air vent

	Excess air
Yes	inside pump
	No
	Chattering from	Yes
	flow switch
	No

Water heat

exchanger board DP_SW11-1 No is ON

Yes

Backup

heater terminal has No 230ACV ( ± 23V)

Yes

Secure water
	Dirt clogging	Replace flow switch
circulation amount
	inside water circuit
	(inside strainer, etc)
	12 M or longer	Fit buffer tank and the
	water pipe to	second pump
Circulation
	a branch, or 5 or
flow shortage	less branches

Set DP_SW11-1 to ON

Power is		No
			Connect backup heater
connect to backup
heater terminal			power cable
	Yes
		Set heater breaker to ON
			Check indoor wiring

Backup	No
heater element		Replace backup heater unit
is conductive	(Backup heater NG)
Yes
TC, TWO, TWI	No
		Replace TC, TWO,
sensor characteristics
	(See Characteristic table on page 101)	and TWI sensors
are correct
Yes
Replace water heat
exchange control board

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