Carrier 09DK054-084 - Manual (Page 29)

START-UP
System Evacuation and Dehydration — Refer
to GTAC II, Module 4, “Dehydration for Proper Evacua­
tion and Dehydration techniques.”
Charging Procedure — Charge to a clear sight glass.
Refer to GTAC II, Module 5 “Charging, Recovery, Recy­
cling, and Reclamation” for proper charging techniques.
Add 10 lbs (4.5 kg) of R-22 over clear sight glass to flood
subcooler sections of the condenser coils. This 10 lbs
(4.5 kg) is added to the total unit charge, and must be pro­
portioned by the percentage of circuits when multiple cir­
cuits are employed. For example, in Table 2, add .67 x
10 lbs (4.5 kg) (approximately 6.7 lbs [3.0 kg]) for the 67%
circuit. Refer to Table 6 for condenser coil refrigerant
circuit data.
Check Operation of Condenser Fan Motor Con­
trols and Rotation of Fans —
Rotation should be
clockwise as viewed from top of unit.
A CAUTION
Before starting unit, be sure wire fan guards are
secured in place over each fan; personal injury may
result.
SERVICE
Cleaning Condenser Coils — Clean coils with a vac­
uum cleaner, fresh water, compressed air, or a bristle brush
(not wire). Units installed in corrosive environments should
have coil cleaning as a part of a planned maintenance sched­
ule. In this type of application, all accumulations of dirt
should be cleaned off the coil.
A CAUTION
Do not use high-pressure water or air. Damage to fins
may result.
Condenser Fans — Each fan is supported by a formed
wire mount bolted to the fan deck and covered with a wire
guard. The exposed end of the fan motor shaft is protected
by grease. If the fan motor must be removed for service or re­
placement, be sure to grease fan shaft, and reinstall fan guard.
For proper performance, fan should be 7/8 in. (22 mm) be­
low the top of the venturi on the fan deck for 60 Hz units,
and 1/2 in. (13 mm) to top of the fan hub for 50 Hz units.
Tighten set screws to 15 ± 1 ft-lbs (20 ± 1 . 3 N-m). Fig­
ure 27 shows the proper position of the mounted fan.
IMPORTANT: Check for proper fan rotation (clock­
wise viewed from above). If rotation needs to be re­
versed on one motor, disconnect main power supply
and switch motor leads at the fan contactor. If rota­
tion needs to be reversed on all motors, disconnect
main power supply and switch two leads at TBl.
Lubrication — Fan motors have permanently lubricated
bearings.
Head Pressure Control — Reduce condensing capac­
ity under low ambient temperature conditions. See Fan
Cycling section below.
FAN CYCLING — Efficient operation of evaporator ther­
mostatic expansion valves require a 90 F (32 C) minimum
saturated condensing temperature when compressors are op­
erating at 100% capacity, 80 F (27 C) for 75% compressor
capacity, and 70 F (21 C) for 50 and 25% compressor
capacity.
The capacity of an air-cooled condenser increases with
increased temperature difference (defined as entering satu­
rated condenser temperature minus entering outdoor-air tem­
perature) and decreases with decreased temperature differ­
ence. A drop in entering outdoor-air temperature results in
a lower saturated condensing temperature. When outdoor-
air temperature drops below the minimum temperatures listed
in Table 7 for standard units, additional head pressure con­
trol is required.
Model 09DK units have fully automatic intermediate-
season head pressure control through condenser fan cycling
using electromechanical fan cycling controls. Standard head
pressure controls will control the 100 and 50/50% con­
denser capacity applications. Head pressure can also be con­
trolled by fan cycling controls supplemented by the acces­
sory Motormaster® III solid-state head pressure controller.
See Motormaster III installation instructions for more infor­
mation. Other circuit split applications (67/33, 33/33/33,
33/33/17/17% capacity splits) will require the accessory fan
control kit which includes a control panel and additional
fan cycling pressure switches. See fan control installation
instructions for more information.
In the standard control scheme, fans 1 and 2 will be on
when there is a call for cooling from the respective coil cir­
cuits. Fans 1 and 2 are non-cycling. On 054 and 064 units,
fans 3 and 4 will be controlled by using a fan cycling pres­
sure switch on each of the primary coil circuits in response
to condensing pressure. On 074 and 084 units, fans 3 and 4
will also be controlled using a fan cycling pressure switch
in each of the primary coil circuits in response to condens­
ing pressure. Fans 5 and 6 will be controlled by using two
air temperature switches, which respond to the outdoor am­
bient temperature. The air temperature switches are located
on the control box shelf. For temperature and pressure set­
ting details, see Table 8.
With respect to the fan cycling pressure switch control,
fans 3 and 4 are on above 260 ± 15 psig (1793 ± 103 kPa)
and off below 160 ± 10 psig (1103 ± 69 kPa). If pressure
is rising between 160 psig (1103 kPa) and 260 psig
(1793 kPa), fans 3 and 4 are off. If pressure is reducing
from 260 psig (1793 kPa) to 160 psig (1103 kPa) fans 3 and
4 are on. With respect to the air temperature switch control
on the 074 and 084 condensers, below 70 ± 3° F
(21.1 ± 1.7° C) outdoor ambient, fans 5 and 6 are off; above
80 ± 3° F (26.7 ± 1.7° C) fans 5 and 6 are on. Between
70 F (21.1 C) and 80 F, (26.7 C) whether fans 5 and 6 are
on or off depends on whether temperature is rising or fall­
ing. If the temperature is rising from 70 F (21.1 C) to 80 F
(26.7 C), fans 5 and 6 are off. If the temperature is falling
from 80 F (26.7 C) to 70 F (21.1 C), fans 5 and 6 are on.
TOP OF VENTURI
ON FAN DECK TOP OF VENTURI
ON FAN DECK
L
HUB
ALL 50-Hz
UNITS
ALL 60-Hz
UNITS
29
NOTE: Fan rotation is ciockwise as viewed from top of unit
Fig. 27 — Condenser Fan Adjustment