5
GO SERIES
point for thermostat wiring, the interface board also
translates thermostat inputs into control commands for
the variable speed programmable ICM-2 DC fan motor
and displays an LED indication of operating status. The
thermostat connections and their functions are as
follows:
Y2 Second Stage Compressor Operation
Y1 First Stage Compressor Operation
G Fan
O Reversing Valve (energized in cooling)
W1 Auxiliary Electric Heat
(runs in conjunction with compressor)
EM/W2 Emergency Heat (electric heat only)
NC Transformer 24 VAC Common
(extra connection)
C1 Transformer 24 VAC Common
(primary connection)
R Transformer 24 VAC Hot
HUM Dehumidification Mode
(not used in GO Series)
If the Geo-Miser unit is being connected to a thermostat
with a malfunction light, this connection is made at the
unit lockout relay.
NOTE:: If the thermostat is provided with a malfunction
light powered off of the common (C) side of the
transformer (such as FHP’s part # 641-068), the unit
must be provided with a malfunction relay (FHP option #
660-006) to properly energize the light. The relay coil will
be wired across the (ALR) and (C) contacts on the unit’s
CCM board and the relay’s normally open contacts
across (ALR) and the malfunction light connection on the
thermostat. If the thermostat is provided with a
malfunction light powered off of the hot (R) side of the
transformer (such as FHP part#641-060), then the
thermostat malfunction light connection should be
connected directly to the (ALR) contact on the unit’s
CCM board.
To the left of the thermostat connection block are a row
of 2 red and 4 green LED’s. These LED’s indicate the
operating status of the unit. They are labeled as follows:
EM (red) Emergency Heat On
W1 (red) Auxiliary Heat On
O (green) Reversing Valve Energized, unit is in
cooling mode
Y2 (green) Second Stage Compressor On
Y1 (green) First Stage Compressor On
G (green) Fan On
Just above the connector block is a single red LED
labeled CFM that will blink intermittently when the unit is
running and may flicker when the unit is off. This LED
indicates the air delivery of the blower at any given time.
Each blink of the LED represent 100 CFM of air delivery
so if the LED blinks 12 times, pauses, blinks 12 times,
etc. the blower is delivering 1200 CFM. Refer to Figure
#7 for factory programmed air delivery settings for the
GO Series.
To the right of the thermostat connection block is a green
LED labeled dehumidify. This feature is not utilized on the
GO Series.
Just above and to the right of the thermostat connection
block are four sets of jumper pins labeled ADJ, DELAY,
HEAT and COOL. The ADJ set of pins are labeled NORM,
(+), (-) and TEST. GO units will all be set on the NORM
position from the factory, however, airflow can be
increased (+) or decreased (-) by 15% from the pre-
programmed setting by relocating the jumper in this
section. The TEST position is used to verify proper motor
operation. If a motor problem is suspected, move the
ADJ jumper to the TEST position and energize G on the
thermostat connection block. If the motor ramps up to
100% power, then the motor itself is functioning normally.
Always remember to replace the jumper to NORM, (+) or
(-) after testing and reset the unit thermostat to restore
normal operation.
NOTE: Do not set the ADJ jumper to the (-) setting when
electric heaters are installed. Doing so may cause the
heaters to cycle on their thermal overload switches,
potentially shortening the life of the switches.
The other three sets of jumper pins are used to select the
proper program in the ICM motor for the unit. Refer to
Figure #7 for the proper jumper placement.
NOTE: Always disconnect power before changing
jumper positions on the interface board and reset the unit
afterward.
To the left of the red and green status LED’s is a row of
1/4” male quick connects. These are used to pass
thermostat inputs on to the rest of the control circuit.
Remember to always turn off unit power at the circuit
breaker before attaching or disconnecting any wiring from
these connections to avoid accidental short circuits that
can damage unit control components.
SAFETY DEVICES AND THE LOCKOUT CIRCUIT:
Each Go Series unit is factory provided with a high
pressure switch, low pressure switch and a condensate
overflow switch. These switches are all normally closed,
opening on a fault condition. If either the high pressure
switch or the condensate overflow switch open, the unit
compressors will shut down immediately. Note that the
blower motor and electric heaters will remain active. The
low pressure switch is deactivated for 90 seconds after
compressor start-up by the low pressure bypass timer.
This prevents nuisance low pressure lockouts during cold
MOTOR PROFILE AIR FLOW TABLE
FAN LOW HIGH AUX. EMERGENCY COOL
MODEL ONLY STEP STEP HEAT HEAT HEAT
AIRFLOW DELAY ADJUST
GO024 550 – 800 900 900 B NORM
GO030 700 – 1000 900 900 A NORM
GO036 850 – 1200 1150 1150 A NORM
GO042 1000 – 1400 2000 2000 D NORM
GO048 1050 1100 1600 2000 2000 C NORM
GO060 1100 1400 2000 2000 2000 B NORM
GO072 1600 1600 2200 2200 2200 A NORM
(Figure #7)
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