Amana VCA Service Instructions Manual page 31

SERVICING
INTEGRATED DEFROST CONTROL
RHA-A-B
COMMON
Y OUT
A
PS2
P
B
S
B
1 LED 2
LED 1
PS1
A
DF
O
OUT
RHA-B-A
FAN
30
60
90
20214301
FAN
90
60
TST
30
AMANA P/N
11164401
CC
PS1
RV
DFS
W C Y
R O
The operation of the integrated defrost control used on the
RHA-A2B & RHA-B-A models is very similar to that of the
solid state control used in the RHA--A2A models. The time
interval is determined by the position of the time select
jumper which is factory set to the specific unit design. The
control will default to 90 minutes if the jumper is missing or
if the jumper is left in the test position for more than 5
minutes. The 20214301 control, used in the RHA-B-A mod-
els is physically smaller than the 11164401 control and does
not include the LED diagnostic display.
The board counts the compressor run time in the heating
mode after the 30/60 control closes. If the 30/60 control
opens, the timer will reset. The board will terminate defrost
when the 30/60 control opens or after 14 minutes compres-
sor run time which ever occurs first. If the thermostat is
satisfied during the defrost cycle, timing is suspended, the
board does not reset.
: RHA30 & 36 A2B units are factory set to 30 minutes.
It is not recommended to change the defrost times on these
E
units. All other models are factory set for 90 minutes and can
be adjusted to accommodate local conditions.
C
During the defrost mode, the fan relay on the control board
R
opens contacts which stop the fan motor. The reversing
valve solenoid is energized to place the unit in the cooling
W
2
mode. Also W2 is energized for signaling electric heat
operation.
O
The defrost mode will be temporally suspended if the
Y
thermostat cycles off, or a pressure switch opens. Upon
closure of pressure switches or resumption of thermostat
demand, defrost activity will resume, as soon as the 5
minute short cycle time is satisfied.
- Placing the jumper in the test position will
accelerate the timing by a factor of 128. With the 30/60
control closed a 90 minute defrost interval will time out in
approximately 42 seconds, a 14 minute defrost will time out
in approximately 7 seconds. If the jumper is in the test
position at power up of the board, the jumper will be ignored.
To reenter the test mode briefly remove the jumper and
replace in test mode.
Some additional features that are built into this control
are:
includes short cycle protection. A five minute lockout will
occur when the 24 VAC power to the contactor is removed
by the thermostat demand cycling off or by the opening of a
pressure switch.
opens, the contactor is locked out for five minutes. After 5
minutes, if the pressure switch is closed, normal operation
will resume.
60 control which bypasses the low pressure control at the
start of the defrost mode to avoid nuisance tripping of the low
pressure switches in this phase of the defrost function. The
RHA-B-A units do not have factory installed pressure
switches.
- The integrated defrost control
- When a pressure switch
The RHA__A2B units have a second 30/
31 Rev 1