Service manual

SERVICING
33
If the valve fails to change its position, test the voltage (24V)
at the valve coil terminals, while the system is on the COOL-
ING cycle.
If no voltage is registered at the coil terminals, check the
operation of the reversing relay and the continuity of the
connecting wires.
If voltage is registered at the coil, tap the valve body lightly
while switching the system from HEATING to COOLING,
etc. If this fails to cause the valve to switch positions, re-
move the coil connector cap and test the continuity of the
reversing valve solenoid coil. If the coil does not test con-
tinuous - replace it.
If the valve is inoperative - replace it.
S-22 REVERSING VALVE REPLACEMENT
Remove the refrigerant charge from the system.
When brazing a reversing valve into the system, it is of
extreme importance that the temperature of the valve does
not exceed 250°F. at any time.
Wrap the reversing valve with a large rag saturated with
water. "Re-wet" the rag and thoroughly cool the valve after
each brazing operation of the four joints involved. The wet
rag around the reversing valve will eliminate conduction of
heat to the valve body when brazing the line connection.
The use of a wet rag sometimes can be a nuisance. There
are commercial grades of heat absorbing paste that may
be substituted.
After the valve has been installed, leak test, evacuate and
recharge.
S-23 CHECKING DEFROST CONTROL BOARD
The Defrost Control Board is an electronic device which is
not field repairable. If a malfunction should occur the com-
plete board must be replaced. The board has anti-short cycle
protection, high and low pressure switch interrupts incor-
porated into the control.
Normal sequence of operation, Cooling Mode.
1. If the compressor has been off for at least 3 minutes
when a call for cool is received, the compressor is im-
mediately energized. The indoor blower is energized
at the cooling speed after a 7 second delay.
2. If the compressor has not been off for at least 3 minutes
when a call for cooling is received, the control waits at
least 3 minutes before energizing the compressor. The
LED will flash 6 times when the compressor is delayed
on the anti-short cycle timer.
4. If power to the control is interrupted, the compressor
will be energized after a 3 minute delay after power is
re-applied to the control. The control will flash 6 times
to indicate the compressor is delayed on the anti-short
cycle timer.
5. The control de-energizes the indoor blower 60 seconds
after the call for cooling is removed.
This control has a self diagnostic feature. Before perform-
ing any test observe the LED indicators and compare to
the chart below for board status.
DIAGNOSTICS
LED 1 LED 2
NORMAL OPERATION
SHORT CYCLE
ALTERNATING
FLASHING
LOCKOUT
ON OFF
BOARD FAILURE
ON ON
BOTH FLASHING
Normal sequence of operation, Heating Mode.
1. If the compressor has been off for at least 3 minutes
when a call for heat is received, the compressor is im-
mediately energized. The indoor blower is energized
at the cooling speed after a 7 second delay.
2. If the compressor has not been off for at least 3 minutes
when a call for heating is received, the control waits at
least 3 minutes before energizing the compressor. The
LED will flash 6 times when the compressor is delayed
on the anti-short cycle timer.
4. If power to the control is interrupted, the compressor
will be energized after a 3 minute delay after power is
re-applied to the control. The control will flash 6 times
to indicate the compressor is delayed on the anti-short
cycle timer.
The following has been simplified in order to illustrate the
Electronic functions:
5. When the defrost thermostat (30/60 control) closes (coil
temperature at approximately 30°F.), the solid state
board becomes programmed.
O
OUT
DF
PS1
PS2
P S 1
COMMON
Y1 OUT
FAN
E C R
W
O Y
2 1
A
B
A
R
G
G
YL-5
SEE
DETAIL 1
TEST
60
DETAIL 1
HEATCRAFT
ADJUSTABLE DEFROST INTERVAL
(FACTORY SETTING AS SHOW N)
30
90
DEFROST
CONTROL
COOLING
SWITCH
RELAY
FUSE
OR
28
GY
55
GY-8
RD-24
DIAGNOSTICS
LED
DEFROST
THERMOSTAT
REVERSING
SOLENOID
O. D.
FAN
MOTOR
+ 24 V
DEFROST CONTROL BOARD