GSX14 Service Manual

SERVICING
128
3. Set thermostat to call for heating. System should go into
defrost within 21 seconds.
4. Immediately remove jumper from test pins.
5. Using VOM check for voltage across terminals "C & O".
Meter should read 24 volts.
6. Using VOM check for voltage across fan terminals DF1
and DF2 on the board. You should read line voltage (208-
230 VAC) indicating the relay is open in the defrost mode.
7. Using VOM check for voltage across "W"/"W2" & "C"
terminals on the board. You should read 24 volts.
8. If not as above, replace control board.
9. Set thermostat to off position and disconnect power
before removing any jumpers or wires.
NOTE: Remove jumper across defrost thermostat before
returning system to service.
COMFORTNET
TM
UNITS:
To check the defrost control for proper sequencing, proceed
as follows: With power ON; unit not running.
1. Set thermostat to call for heating.
2. Press TEST and RECALL buttons simultaneously for
approximately 3 seconds, then release them. System
should go into defrost immediately.
3. Using VOM check for voltage across terminals "C & O".
Meter should read 24 volts (skip this step if system a fully
communicating system)
4. Visually inspect to see that the frost is gradually melting
on the coil and the compressor is running.
5. Using VOM check for voltage across "W2 & C" terminals
on the board. You should read 24 volts.
6. If not as above, replace control board.
7. Set thermostat to off position and disconnect power
before removing any jumpers or wires.
S-25 TESTING DEFROST THERMOSTAT
LEGACY MODELS ONLY:
1. Install a thermocouple type temperature test lead on the
tube adjacent to the defrost control. Insulate the lead
point of contact.
2. Check the temperature at which the control closes its
contacts by lowering the temperature of the control. Part
# 0130M00009P which is used on 2 and 2.5 ton units
should close at 34°F ± 5°F. Part # 0130M00001P or
B1370803 which is used on 3 thru 5 ton units should close
at 31°F ± 3°F.
3. Check the temperature at which the control closes its
contacts by lowering the temperature of the control. Part
# 0130M00085, which is used onunits with 5 mm coils,
should close at 30°F ± 5°F.
4. Check the temperature at which the control opens its
contacts by raising the temperature of the control. Part
#0130M00009P which is used on 2 and 2.5 ton units
should open at 60°F ± 5°F. Part # 0130M00001P or
B1370803 which is used on 3 thru 5 ton units should open
at 75°F ± 6°F.
5. Check the temperature at which the control opens its
contacts by raising the temperature of the control. Part
# 0130M00085, which is used on units with 5 mm coils,
should open at 60°F ± 5°F.
6. If not as above, replace control.
S-26 TESTING TEMPERATURE SENSORS
(COMFORTNET READY MODELS ONLY)
The ASXC and DSXC ComfortNet ready air conditioner
models are factory equipped with an outdoor air tempera-
ture (OAT) sensor. The OAT sensor allows the outdoor air
temperature to be displayed on the CTK0* thermostat when
used with the ASXC and DSXC models.
The ASZC and DSZC ComfortNet ready heat pump models
are equipped with both an outdoor air temperature (OAT)
sensor and an outdoor coil temperature (OCT) sensor. The
OAT provides the balance point temperature in heat pump
systems (air handler w/electric heat + heat pump) and dual
fuel systems. The OCT sensor is provides the outdoor coil
temperature and is used in determining defrost cycles.
To check either the outdoor air or outdoor coil temperature
sensors:
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing. Multiple power sources
may be present. Failure to do so may
cause property damage, personal injury
or death.
1. Disconnect power to the air conditioner or heat pump.
2. Disconnect the sensor from the unitary (UC) control.
3. Connect an ohmmeter across the sensor terminals. The
ohmmeter should read be 10kΩ, +/-10%, at 75°F. Re-
place the sensor if the sensor is open, shorted, or outside
the valid resistance range.
T, °F RW@T T, °F RW@T T, °F RW@T T, °F RW@T T, °F RW@T
-40 336,000 5 72,940 50 19,903 95 6,530 140 2,488
-31 242,700 14 55,319 59 15,714 104 5,327 149 2,083
-22 177,000 23 42,324 68 12,493 113 4,370 158 1,752
-13 130,400 32 32,654 77 10,000 122 3,603 167 1,480
-4 97,060 41 25,396 86 8,056 134 2,986 176 1,255
Ohm Reading of Communicating Outdoor Unit Sensors
S-40 MBR/AR*F ELECTRONIC BLOWER TIME
DELAY RELAY
The MBR/AR*F contains an Electronic Blower Time Delay
Relay board, B1370735. This board provides on/off time
delays for the blower motor in cooling and heat pump heating
demands when “G” is energized.