Panasonic CU-4KE24NBU Protective Functions, Overload prevention during heating, Freeze prevention

7-2. Protective Functions

Overload prevention during heating

During HEAT operation, the temperature of the indoor heat exchanger is used to control the frequency and lessen the load on the compressor before the protective device is activated.

Indoor heatexchanger	temperature °F(°C)	Approx.		A		Indoor heat exchanger
		127				A. Control start
		(53)				B. Control end
		Approx.				B
		117
		(47)
			a	b	c	d

a.Area: Automatic capacity control

b.When Point A has been exceeded, the operation frequency is reduced by a certain proportion.

c.Area: Frequency increase is prohibited.

d.At Point B and below, overload prevention is ended and control is the same as in the a area.

Freeze prevention

During COOL or DRY operation, freezing is detected and operation is stopped when the temperature of the indoor heat exchanger matches the conditions below.

1.Freeze-prevention operation is engaged when the temperature of the indoor heat exchanger is below 43°F(6°C).

2.Restart after freeze-prevention operation occurs when the temperature of the indoor heat exchanger reaches 46°F(8°C) or above.

Indoor heat exchanger	temperature °F(°C)	46				C
		(8)
		43		A	B
		(6)
		36
		(2)	*
			a	b	c	d

a.Area: Automatic capacity control

b.When the temperature drops below Point A, the operation frequency is reduced by a certain proportion.

c.Area: Frequency increase is prohibited.

d.When the temperature reaches Point C or above, freezing prevention is ended and control is the same as in the a area.

*When the temperature drops to below 36°F(2°C) (continuously for 2 minutes or longer), the compressor stops. Once the freeze condition is detected, the air conditioner will work less than the maximum frequency until it is turned off.

Cold-air prevention during heating

During heating, the fan speed is set to "LL" (very low) or stopped. As the temperature of the indoor heat exchanger rises, the fan speed is changed to the set speed.

Fan speed [rpm]						Outdoor air temp.
			The fan speed is increased depending
			on the outside air temperature. (*1)
H +							TO1
							TO2
H							TO3
		At stability of operation
					At start of operation
LL
Stopped
	77			86	TC1	100
	(25)			(30)		(38)

Indoor heat exchanger

temperature °F(°C)

NOTE

•The fan speed is forcibly changed to "LL" beginning 30 seconds after the thermostat turns OFF.

•At stability of operation refers to operation when the room temperature has approached the set temperature.

•When HEAT operation starts, the indoor fan is stopped until the temperature of the indoor heat exchanger reaches 68°F(20°C) or higher, or until the room temperature reaches 59°F(15°C) or higher.

*1 It is applied only to CS-MKE9NB4U and CS-MKE12NB4U. This function is enabled when the automatic operation is being performed and the "Automatic Fan Speed" has been selected. The fan speed might be increased during the automatic operation. However, it is not the abnormal condition.

TC1 : CS-KE18NB4UW 104°F (40°C) CS-MKE9NB4U, CS-MKE12NB4U 91°F (33°C)

TO1 : 35.6°F (2°C) or less

TO2 : 35.6°F (2°C) to 53.6°F (12°C)

TO3 : 53.6°F (12°C) or more

30