Whirlpool W4GH6 Adjust Defrost System, Time Delay, Pressure Switch Circuit, Defrost Control Board

Time Delay

The time delay is 5 minutes long. The delay helps to protect the compressor from short cycling in case the power to the heat pump is interrupted or a pressure switch opens. The delay is bypassed by placing the timer select jumper across the TEST pins for 0.5 seconds.

Pressure Switch Circuit

The defrost control includes LO-PS terminals to connect an optional low pressure (loss of charge pressure) switch. A high pressure switch (optional) can be connected to the HI PS

Adjust Defrost System

Defrost Control Board

Optional high pressure switch connections

NOTE: To add the pressure switch, remove the factory-installed jumper.

	P1		FAN
A	30
	60	C2
	90		K1 Relay

TEST

terminals. See “Defrost Control Board” in the “Adjust Defrost System” section.

During a single demand cycle, the defrost control will lock out the heat pump after the fifth time that the circuit is interrupted by any pressure switch wired to the control board. In addition,

the diagnostic LEDs will indicate a locked-out pressure switch after the fifth occurrence of an open pressure switch. See Defrost Control Board Diagnostic LEDs chart later in this section.

B

C P5 U1 U2

DO-OUT

DS1

DS2

K2 Relay

P2

H

The heat pump will remain locked out until power to the board is interrupted, then re-established, or until the jumper is applied to the TEST pins for 0.5 seconds.

NOTE: The defrost control board ignores input from the low pressure switch terminals during:

■ TEST mode

■ Defrost cycle

LO-PS

E

DF

F C5

Y1-OUT

HI-PSK3 Relay

LW1 C

24V L I

R

O

Y1

■	90-second start-up period
■	First 90 seconds after the reversing valve switches heat/cool
	modes

NOTE: If the TEST pins are jumpered and the 5-minute delay is being bypassed, the LO PS terminal signal is not ignored during the 90-second start-up period.

Defrost Control Board Diagnostic LEDs

	Green	Red LED
Mode	LED (DS2)	(DS1)
No Power to Board	Off	Off
Normal Operation/Power to Board	Simultaneous Slow Flash
Short Cycle Lockout	Alternating Slow Flash
Low Pressure Switch Fault	Off	Slow Flash
Low Pressure Switch Lockout	Off	On
High Pressure Switch Fault	Slow Flash	Off
High Pressure Switch Lockout	On	Off

G

	P6
TST PS DF C R O Y1
A. Defrost time setting pins	F. Defrost thermostat
B. Test pins	G. High pressure switch (optional)
C. Compressor delay pins	H. Diagnostic LEDs
D. Reversing valve	I. Low voltage terminal strip
E. Low pressure switch (optional)	connections

Adjust Time Between Defrost Cycles

WARNING

Electrical Shock Hazard

Disconnect power before servicing.

Replace all parts and panels before operating.

Failure to do so can result in death or electrical shock.

1.Disconnect power.

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