6
QuietShift
Quiet shift is a field selectable defrost mode (factory set to OFF),
which will eliminate occasional noise that could be heard at the
start of defrost cycle and restarting of heating cycle. It is selected
by placingDIP switch 3 on defrost board(see Fig. 9) in the ON
position.
When Quiet Shift switch is placed in ON position, and a defrost is
initiated, the following seq uence of operation will o ccur.R eversing
valve willenergize, compressor willturn off for 30 seconds, and
then turn back on to complete defrost. At the start of heating after
conclusion of defrost, reversing valve will de--energize,
compressorwill turn off for another 30 seconds,and the fan will
turnoff for 40 seconds,before starting in theheating mode.
Defrost
The defrost controlis a time/temperature control which hasfield
selectablesettingsof 30, 60, 90,or 120 minutes, factory setto 90
minutes.These settingsrepresent the amountof timethatmust pass
after closure of the defrost thermostat before the d efrost sequence
begins.
The defrostthermostat senses coil temperaturethroughout the
heating cycle. When the coil temperature reaches the defrost
thermostat setting of approximately 32 _F(0_C), it will close,
which energizes the DFT terminal and b egins the defrost timing
sequence. When the DFT has been energized for the selected time,
the defrost cycle begins. Defrost cycle is terminated wh en defrost
thermostatopens, or automaticallyafter10 minutes.
DefrostSpeedup
Toinitiate a forced defrost,sp eedup pins (J1) must be shortedwith
a flathead screwdriver for 5 seconds and RELEASED.Ifthe
defrostthermostat is open, a short defrost cyclewill be observed
(actuallengthdepends on Quiet Shift switchposition). When Quiet
Shiftis off, only a short30 second defrost cycle is observed.With
Quiet Shift ON,the speedup sequence is one minute; 30 second
compressoroff period followed by 30 secondsof defrost with
compressor operation.When returning to heating mode, the
compressorwill turn off for an additional30 seconds and the fan
for40 seconds.
If the defrost thermostat is closed, a complete defrost cycle is
initiated. If the Quiet Shift switch is turned o n, the compressor will
beturned off for two 30 secondintervals as explainedpreviously.
OF2
HK32EA003
OF1
ON
QUIET
SHIFT
120
30
60
60
30
90
INTERVAL TIMEROFF
P3
DFT
O R W
2
Y C
T2 C C O
DFT
T1 Y P1 J1
SPEEDUP
Speedup
Pins
Defrost interval
DIP switches
Quiet
Shift
A05378
Fig. 9 -- Defros t Control
Table3 – DefrostControl Speedup--TimingSequence
Check Charge
Factorycharge amount and desiredsubcooling are shown on unit
rating plate. Charging method is shown on information plate inside
unit. To properly check or adjust charge, conditions must be
favorable for subcooling charging. Favorable conditions exist
when the outdoor temperature is between 70_F and 100_F
(21.11_C and 37.78_C), and the indoortemperature is between
70_F and 80_F (21.11_C and 26.67_C). Follow the procedure
below:
Unitis factory chargedfor 15ft (4.57 m) of lineset.Adjust charge
by adding or removing0.6 oz/ft (.018 kg/m) of 3/8 liquidline
aboveor below 15ft (4.57 m) respectively.
For standardrefrigerant linelengths (80 ft/24.38 m or less),allow
systemto operatein cooling mode at least15 minutes. If conditions
arefavorable, check system chargeby subcoolingmethod. If any
adjustmentis necessary,adjust charge slowly and allow system to
operate for 15 minutes to stabilize before declaring a properly
charged system.
If the indoor temperature is above 80_F (26.67_C), and the
outdoortemperature is in thefavorable range, adjust systemcharge
byweight based on line lengthand allow the indoortemperature to
dropto 80_F (26.67_C) before attemptin g toch eck systemch arge
bysubcooling method as describedabove.
Ifthe indoor temperature is below70_F (21.11_C), or the outdoor
temperatureis not in the favorablerange, adjust charge for line set
lengthabove or below 15ft(4.57 m) only. Chargelevel should then
beappropriate for the system toachieve rated capacity.The charge
levelcould then be checked at anothertime when the both indoor
andoutdoor temperaturesare in a more favorable range.
NOTE: If line length is beyond80 ft (24.38 m) or greater than 20
ft (6.10 m) vertical separation, See Long Line Guideline for
special charging requirements.

HeatingCheck Chart Procedure

To check system operation during heating cycle, refer to the
HeatingCheck Chart on outdoor unit. This chart indicateswhether
aco rrectrelation ship exists between system operating pressure and
air temperatureentering indoor and outdoorunits. If pressure and
temperaturedo not match on chart,system refrigerant chargemay
notbe correct. Do not use chartto adjust refrigerantcharge.
Final Checks
IMPORTANT:Beforeleaving job, be sure to do the following:
1. Ensure that all wiring is routed away from tubin g and sheet
metaledges to prevent rub--throughor wirepinching.
2. Ensure that all wiringand tubing is secure in unit before
adding panels and covers. Securely fasten all panels and
covers.
3. Tighten service valve stem caps to 1/12--turn past finger
tight.
4. Leave Owner’s Manual with owner. Explain system
operation and periodic maintenance requirements outlined
in manual.
5. Fill out Dealer Installation Checklist and place in cu stomer
file.
CARE AND MAINTENANCE
For continuing high performance and to minimize possible
equipment failure, periodic maintenan ce must be performed on this
equipment.
Frequency ofmaintenance may vary depending upon geographic
areas, such as coastal applications. S ee Users Manual for
information.
25HCB3 / 25HCC5