Carrier 50HJQ016 Installation, Start-Up And Service Instructions Manual page 19

Fig. 30 — Fan Performance Using Accessory
Power Exhaust
Outdoor Fans and Motors —
factory set. Refer to Outdoor-Fan Adjustment section on
page 22 as required.
Return-Air Filters —
Check that correct filters are
installed in filter tracks. See Table 1. Do not operate unit with-
out return-air filters.
Outdoor-Air Inlet Screens —
must be in place before operating unit.
Accessory Field-Installed EconoMi$er Adjust-
ment —
Remove filter access panel. Check that outdoor-air
damper blades are closed and return-air damper blades are open.
EconoMi$er operation and adjustment is described in Base
Unit Operation and EconoMi$er Adjustment sections on this
page and page 23, respectively.
Base Unit Operation
COOLING, UNITS WITHOUT ECONOMI$ER — With unit
main power on, set thermostat to COOL position and desired
room temperature. Set fan switch at AUTO. (on demand) or
ON (continuous) position.
On a rise in room temperature, cooling contact no. 1 in the
thermostat closes. The indoor and outdoor fan motors start. If
the 5-minute compressor time-delay (CTD) on the defrost
board (DB) is satisfied, then compressor no. 1 contactor is
energized and compressor no. 1 will start. Compressor no. 1
cycles on demand of the thermostat to satisfy room conditions.
Each time the cooling contactor no. 1 opens, the CTD starts the
5-minute delay.
On 50HJQ016 units, with an additional rise in room temper-
ature, cooling contactor no. 2 in the thermostat closes, energiz-
ing compressor contactor no. 2. Compressor no. 2 starts and
cycles on demand of the thermostat to satisfy the occupied
space demands.
COOLING, UNITS WITH ECONOMI$ER — When the OAT
is above the ECON SP set point and the room thermostat calls
for Stage 1 cooling (R to G + Y1), the indoor-fan motor (IFM)
is energized and the EconoMi$er damper modulates to mini-
mum position. The compressor contactor and outdoor-fan
contactor (OFC) are energized to start the compressor and
outdoor-fan motors (OFM). After the thermostat is satisfied,
the damper modulates to the fully closed position when the
IFM is deenergized.
When the OAT is below the ECON SP setting and the room
thermostat calls for Stage 1 cooling (R to G + Y1), the
EconoMi$er modulates to the minimum position when the
IFM is energized. The EconoMi$er provides Stage 1 of cooling
by modulating the return and outdoor-air dampers to maintain
a 55 F supply air set point. If the supply-air temperature (SAT)
is greater than 57 F, the EconoMi$er modulates open, allowing
a greater amount of outdoor air to enter the unit. If the SAT
drops below 53 F, the outdoor air damper modulates closed to
Fans and motors are
Outdoor-air inlet screens
19
reduce the amount of outdoor air. When the SAT is between 53
and 57 F, the EconoMi$er maintains its position.
If outdoor air alone cannot satisfy the cooling requirements
of the conditioned space, and the OAT is above the MECH
CLG LOCKOUT set point, the EconoMi$er integrates free
cooling with mechanical cooling. This is accomplished by the
strategies below.
NOTE: Compressor has a two-minute Minimum On, Mini-
mum Off, and interstage delay timer.
1. If Y1 is energized, and the room thermostat calls for Y2
(2-stage thermostat), the compressor and OFC are ener-
gized. The position of the EconoMi$er damper is main-
tained at its current value.
2. If Y1 is energized for more than 20 minutes, and Y2 is
not energized (whether or not a 2-stage thermostat is
used), the compressor and OFCs are energized. The
position of the EconoMi$er damper is maintained at its
current value.
3. If Y1 is energized, and the compressor no. 1 is already en-
ergized (see Step 2) and the room thermostat calls for Y2,
compressor no. 1 continues to operate. If Y2 remains
energized for more than 20 minutes, compressor no. 2 is
energized.
NOTE: Unloaded compressor (014) or compressor no. 2 (016)
cannot be energized unless there is a signal for Y2 from the
space thermostat.
4. If unloader (014) compressor no. 2 (016) is energized, and
the Y2 signal from the thermostat is satisfied, compressors
1 and 2 (or unloader) are deenergized. Re-asserting Y2
will start compressor no. 1 and (after a 20-minute inter-
stage delay) unloader (014) or compressor no. 2 (016).
5. If compressor no. 1 is energized and the thermostat is sat-
isfied, the compressor no. 1, the OFMs, and IFM are
deenergized and the EconoMi$er modulates closed.
When the OAT is below the MECH CLG LOCKOUT set
point, the compressors remain off.
HEATING, UNITS WITHOUT ECONOMI$ER — With unit
main power on, set thermostat at HEAT position and desired
room temperature. Set fan switch at AUTO. (on demand) or
ON (continuous) position.
On a drop in room temperature, heating contact no. 1 in the
thermostat closes, energizing heat relay (HR), reversing valve
relay (RVR), reversing valve solenoids (RVS1 and RVS2) and
compressor no. 2 contactor. Compressor (50HJQ014) or com-
pressor no. 2 (50HJQ016) and indoor and outdoor fan motors
start. If the 5-minute CTD on the DB is satisfied, then compres-
sor no. 1 contactor is energized and compressor no. 1 will start.
On units equipped with electric heat, when additional heat is
needed, heating contactor no. 2 in the thermostat closes, ener-
gizing W2.
HEATING, UNITS WITH ECONOMI$ER — With unit main
power on, set thermostat at HEAT position and desired room
temperature. Set fan switch at AUTO. (on demand) or ON
(continuous) position.
On a drop in room temperature, heating contact no. 1 in the
thermostat closes, energizing heat relay (HR), reversing valve
relay (RVR), reversing valve solenoids (RVS1 and RVS2) and
compressor no. 2 (50HJQ016) contactor. Compressor no. 2
(50HJQ016) and indoor and outdoor fan motors start. If the
5-minute compressor time delay (CTD) on the defrost board
(DB) is satisfied, then compressor (50HJQ014) or compressor
no. 1 (50HJQ016) contactor is energized and compressor will
start. The outdoor-air damper stays at vent position while the
indoor fan is operating.
On units equipped with electric heat, when additional heat is
needed, heating contactor no. 2 in the thermostat closes, ener-
gizing W2.