Carrier 50JZ-A - Manual (Page 17)

17
OF2
OF1
ON
QUIET SHIFT
120
30 60
60 30
90
INTER
V
AL
TIMER
OFF
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
A08020
Fig. 17 -- Defrost Control
Step 3 — Defrost Control
Quiet Shift
Quiet Shift is a field--selectable defrost mode, which will eliminate
occasional noise that could be heard at the start of defrost cycle and
restarting of heating cycle. It is selected by placing DIP switch 3
(on defrost board) in ON position.
When Quiet Shift switch is placed in ON position, and a defrost is
initiated, the following sequence of operation will occur. Reversing
valve will energize, outdoor fan will turn off, compressor will turn
off for 30 sec and then turn back on to complete defrost. At the
start of heating after conclusion of defrost reversing valve will
de--energize, compressor will turn off for another 30 sec, and the
outdoor fan will stay off for 40 sec, before starting in the Heating
mode.
Defrost
The defrost control is a time/temperature control which includes a
field--selectable time period (DIP switch 1 and 2 on the board)
between defrost cycles of 30, 60, 90, or 120 minutes (factory set at
60 minutes). To initiate a forced defrost, two options are available
depending on the status of the defrost thermostat.
If defrost thermostat is closed, speed--up pins (J1) must be shorted
by placing a flat head screw driver in between for 5 sec and
releasing, to observe a complete defrost cycle. When the Quiet
Shift switch is selected, compressor will be turned off for two 30
sec intervals during this complete defrost cycle, as explained
previously. When Quiet Shift switch is in factory default OFF
position, a normal and complete defrost cycle will be observed.
If defrost thermostat is in open position, and speedup pins are
shorted (with a flat head screw driver) for 5 sec and released, a
short defrost cycle will be observed (actual length is dependent
upon the selected Quiet Shift position). When Quiet Shift switch is
in ON position, the length of defrost is 1 minute (30 sec
compressor off period followed by 30 sec of defrost with
compressor operation). On return to heating operation, compressor
will again turn off for an additional 30 sec and the outdoor fan for
40 sec. When the Quiet Shift is in OFF position, only a brief 30
sec. cycle will be observed.
NOTE: Unit will remain in defrost until defrost thermostat
reopens at approximately 65_F +/-- 5_F (18_C +/-- 2.8_C) coil
temperature at liquid line or remainder of defrost cycle time.
MAINTENANCE
To ensure continuing high performance, and to minimize the
possibility of premature equipment failure, periodic maintenance
must be performed on this equipment. This heat pump unit should
be inspected at least once each year by a qualified service person.
To troubleshoot unit, refer to Table 7.
NOTE: TO EQUIPMENT OWNER: Consult your local dealer
about the availability of a maintenance contract.
50J
Z
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A