11
A14021
Fig. 16 -- AOC Control Board
The control board accumulates compressor run time. As the
accumulated run time approaches the selected defrost interval time,
the control board monitors the coil temperature sensor for a defrost
demand. If a defrost demand exists, a defrost cycle will be initiated
at the end of the selected time interval. A defrost demand exists
when the coil temperature is at or below 32_F(0_C) for 4 minutes
during the interval. If the coil temperature does not reach 32_F
(0_C) within the interval, the interval timer will be reset and start
over.
S Upon initial power up the first defrost interval is defaulted to 30
minutes. Remaining intervals are at selected times.
S Defrost is only allowed to occur below 50_F(10_C) outdoor
ambient temperature.
The defrost cycle is terminated as described below.
S When OAT is > 25 _F(+3.89_C), defrost terminates if outdoor
coil temperature (OCT) > 60_F (+15.6_C). And a minimum of 2
minutes defrost length.
S When O AT ≥ 25_F(+3.89_C), defrost will terminate if OCT is
>45_F(+4.4_C) and a minimum o f 2 minutes defrost length.
S Or 10 minutes has passed.
At the defrost termination, the outdoor fan will turn on 10 seconds
before the reversing valve switching.
NOTE: Compressor speed during defrost will go to defrost speed.
Step 12 — Check Charge
Charge in CHARGING mode (communicating only)
Unit is factory charged for 15ft (4.57 m) of lineset. If any
refrigerant charge adjustment is required due to the user inputted
line set length or indoor coil, the UI will calculate and display the
target subcooling and the amount of additional charge to be added.
Therefore, the UI is your source of information for charging the
system correctly. Refrigerant charge adjustment amount for adding
or removing 0.6 oz/ft (17.74 g/m) of 3/8 liquid line above or below
15ft (4.57 m) respectively . Perform a final charge check only when
in cooling and OD is between 65_F(18_C) and 100_F(38_C).
The use of a commercial charge metering device (restrictor) such as
Imperial liquid low side charger model 535 --C or Watsco
ChargeFaster model CH200 is recommended when adding
refrigerant to an operating system. This prevents potential damage
of liquid slugging of the compressor and allows the subcooling to
stabilize quicker.
Charging using the subcooling method optimizes charge volume
and is preferred if possible. If the outdoor temperature is between
65_F -- 100_F (18.3_C -- 37.8_C) and indoor temperature is 70_F
-- 8 0 _F (21.1_C -- 26.7_C), the option to further adjust charge
using “service valve subcool” will be available in the “charging
mode selection” screen. If temperatures are outside of range, this
option will be greyed out and not selectable.
Initial start--up can be performed using calculated charge only and
once conditions are within range, the ”Service Valve Subcool”
option will become selectable.
Once start is selected the system will operate in a preset mode until
“done” is selected. Wait for required stabilization time then check
subcooling at service valve.
Adjust charge as required to meet target service valve subcooling
shown on screen +/--1 degree. If any adjustment is necessary , add
or remove the charge slowly (no greater than .5 lb per minute) and
allow system to operate for 25 minutes to stabilize, before
declaring a properly charged system.
A14573
Fig. 17 -- Adjusting Charge Using Service Valve Subcool
A14574
Fig. 18 -- Service Valve Subcool Target Value
A14575
Fig. 19 -- Stabilization Time
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations .
Catalog No: 25
N
8 --- 5 S I
Replaces: 25VNA8---4SI
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