Page 13
XP13 SERIES
Charging
The XP13 unit is factory−charged with enough HFC−410A
refrigerant to accommodate a 15−foot length of refrigerant
piping. Charge should be checked and adjusted using the
tables provided on the charging procedure sticker on the
unit access panel. Detailed information is given in the
XP13 Installation and Service Procedures manual, which
is available on DaveNet.
Defrost System
The defrost system includes a defrost thermostat (S6) and
a defrost control (CMC1).
DEFROST CONTROL (CMC1)
This defrost control includes the combined functions of a
time/temperature defrost control, defrost relay, time delay,
diagnostic LEDs, and a terminal strip for field wiring con-
nections.
24V TERMINAL
STRIP
CONNECTIONS
DIAGNOSTIC
LEDS
HIGH PRESSURE
SWITCH
TEST
PINS
DEFROST TIMING
PINS (P1)
REVERSING
VALVE
DEFROST
THERMOSTAT (S6)
LOW PRESSURE
SWITCH
COMPRESSOR
DELAY PINS
S4
S87
SERVICE LIGHT
CONNECTIONS
DEFROST CONTROL (CMC1)
FIGURE 14
The defrost control provides automatic switching from nor-
mal heating operation to defrost mode and back. When the
defrost thermostat is closed, the control accumulates com-
pressor run time at 30, 60 or 90 minute field adjustable in-
tervals. When the selected compressor run time interval is
reached, the defrost relay is energized and defrost begins.
Defrost Control Timing Pins (P1)
Each timing pin selection provides a different accumu-
lated compressor run time period for one defrost cycle.
This time period must occur before a defrost cycle is initi-
ated. The defrost interval can be adjusted to 30 (T1), 60
(T2), or 90 (T3) minutes (see figure 14). The maximum
defrost period is 14 minutes and cannot be adjusted.
NOTE Defrost control part number is listed near the
P1
timing pins.
S
Factory default is 90 minutes.
S
If the timing selector jumper is missing, the defrost
control defaults to a 90−minute defrost interval.
Compressor Delay (P5)
The defrost control has a field−selectable function to re-
duce occasional sounds that may occur while the unit is
cycling in and out of the defrost mode.
The compressor will be cycled off for 30 seconds going in
and out of the defrost mode when the compressor delay
jumper is installed.
NOTE The 30-second compressor feature is ignored
when jumpering the TEST pins.
Time Delay
The timed-off delay is five minutes long. The delay helps to
protect the compressor from short-cycling in case the pow-
er to the unit 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.
Test Mode (P1)
A TEST option is provided for troubleshooting.
The TEST
mode may be started any time the unit is in the heating
mode and the defrost thermostat is closed or jumper-
ed.
If the jumper is in the TEST position at power-up, the
defrost control will ignore the test pins. When the jumper is
placed across the TEST pins for two seconds, the defrost
control will enter the defrost mode. If the jumper is re-
moved before an additional 5−second period has elapsed
(7 seconds total), the unit will remain in defrost mode until
the defrost thermostat opens or 14 minutes have passed. If
the jumper is not removed until after the additional 5−sec-
ond period has elapsed, the defrost will terminate and the
test option will not function again until the jumper is re-
moved and re−applied.
Service Light Connection
The defrost control includes terminal connections for a ser-
vice light which provides a signal that activates the room
thermostat service light during periods of inefficient opera-
tion.
Defrost Control Diagnostic LEDs
The defrost board uses two LEDs for diagnostics. The
LEDs flash a specific sequence according to the condition.
TABLE 2
DEFROST CONTROL (CMC1) DIAGNOSTIC LEDS
Mode
Green LED (DS2)
Red LED (DS1)
No power to con-
trol
OFF
OFF
Normal operation /
power to control
Simultaneous Slow FLASH
Anti-short cycle
lockout
Alternating Slow FLASH
High pressure
switch fault
Slow FLASH
OFF
High pressure
switch lockout
ON
OFF
HIGH PRESSURE SWITCH (S4)
This unit is equipped with a high pressure switch which is
located on the liquid line. The SPST, normally closed pres-
sure switch opens when liquid line pressure rises above
the factory setting of 590 + 15 psig and automatically re-
sets at 418 + 15 psig.
