Ducane (HVAC) 2HP13/14 - Manual (Page 8)

506162-02 Issue 0847 Page 8 of 14
intervals. If the defrost therm ostat is closed when the
selected com pressor run tim e interval ends (call for
defrost), the defrost relay is energized and defrost begins.
The factory setting is 60 m inutes. However, if frost
accum ulation is easily cleared, the optim um efficiency
setting is 90 m inutes.
Outdoor Unit Defrost Control Board
Defrost Control Tim ing Pins
Each tim ing pin selection provides a different
accum ulated com pressor run tim e period for one defrost
cycle. This tim e period m ust occur before a defrost cycle
is initiated. The defrost interval can be adjusted to 30
(/T1), 60 (T2), or 90 (T3) m inutes. The defrost tim ing
jum per is factory-installed to provided a 90-m inute defrost
interval. If the tim ing selector jum per is not in place the
control defaults to a 90-m inute defrost interval. The
m axim um defrost period is 14 m inutes and cannot be
adjusted.
A TEST option is provided for troubleshooting. The
TEST mode may be started any tim e the unit is in the
heating m ode and the defrost therm ostat is closed or
jumpered. If the jum per is in the TEST position at power-
up, the control will ignore the test pins. W hen the jum per
is placed across the TEST pins for 2 seconds, the control
will enter the defrost m ode. If the jum per is rem oved
before an additional 5 second period has elapsed ( 7
seconds total), the unit will rem ain in defrost m ode until the
defrost therm ostat opens or 14 m inutes have passed. If
the jum per is not rem oved until after the additional 5
second period has elapsed, the defrost will term inate and
the test option will not function again until the jum per is
rem oved and re-applied.
Com pressor Delay
The defrost board has a field-selectable function to
reduce occasional sounds that m ay occur while the unit is
cycling in and out of the defrost m ode. T he com pressor
will be cycled "off" for 30 seconds going in and out of the
defrost m ode when the com pressor delay jum per is
rem oved.
NOTE: The 30 second "off" cycle is not functional when
jum pering the TEST pins.
Tim e Delay
The tim ed-off delay is 5 m inutes long. The delay help to
protect the com pressor from short-cycling in case the
power to the unit is interrupted or a pressure switch opens.
The delay is bypassed by placing the tim er select jum per
across the TEST pins for 0.5 seconds.
Pressure Sw itch Circuit
The defrost control incorporates 2 pressure switch
circuits. The optional high pressure switch connects to the
boards HI PS term inals. The low pressure switch is factory
installed.
During a single dem and cycle, the defrost control will lock
out the unit after the fifth tim e 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. The unit will rem ain locked out until
power to the board is interrupted, then re-established or
until the jum per is applied to the T EST pins for 0.5
seconds.
NOTE: The defrost control board ignores input from the
low-pressure switch term inals as follows:
! During the TEST m ode,
! During the defrost cycle,
! During the 90 second start-up period,
! and for the first 90 seconds each tim e the reversing
valve switches heat/cool m odes. If the TEST pins
are jum pered and the 5 minute delay is being by-
passed, the LO PS term inal signal is not ignored
during the 90 second start-up period.
Diagnostic LEDS
T he defrost board uses 2 LEDs for diagnostics. The
LEDs flash a specific sequence according to the condition.
Defrost Control board Diagnostic LED
Mode Green LED (DS2) Red LED (DS1)
No power to control OFF OFF
Normal operation/
power to control
Simultaneous Slow FLASH
Anti-short cycle
lockout
Alternating Slow FLASH
Low pressure switch
fault (Optional)
OFF Slow FLASH
Low pressure switch
lockout (Optional)
OFF ON
High pressure switch
fault (Optional)
Slow FLASH OFF
High pressure Switch
lockout (Optional)
ON OFF