Residential Air Conditioners and Heat Pumps Using R-22 and Puron® Refrigerant: Application Guideline and Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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3. Turn on power to outdoor unit.
4. Restart unit in heating.
5. Within a few minutes, liquid line temperature drops within a range
causing defrost thermostat contacts to close. Temperature range is
from 33°F to 27°F. Notice temperature at which ohmmeter reading
goes from ¥ to zero ohms. Thermostat contacts close at this point.
6. Short between the speed-up terminals using a small slotted
screwdriver.
7. Unit changes over to defrost within 21 sec (depending on timing
cycle setting). Liquid line temperature rises to range where defrost
thermostat contacts open. Temperature range is from 60°F to 70°F.
Resistance goes from zero to ¥ when contacts are open.
8. If either opening or closing temperature does not fall within above
ranges or thermostat sticks in 1 position, replace thermostat to
ensure proper defrost operation.
NOTE:
With timing cycle set at 90 minutes, unit initiates defrost within
approximately 21 sec. When you hear the reversing valve changing
position, remove screwdriver immediately. Otherwise, control will
terminate normal 10-minute defrost cycle in approximately 2 sec.
HK32EA009 DEFROST CONTROL
The HK32EA009 is used in place of the HK32EA001/007 boards when
an outdoor ECM motor is being used. The functionality of these controls
are identical except the HK32EA009 uses 24v to turn the outdoor motor
on/off at the ODF terminal. The 24v signal is internal to the board and
usually originates from the indoor transformer. The other side (common)
of the ECM motor is connected directly to the 24v common side of the
contactor.
HK32EA003 / 008 DEFROST CONTROL
The HK32EA003/008 defrost control is used in most Preferred Series
heat pumps with Puron refrigerant. Its features include selectable defrost
intervals of 30, 60, 90, & 120 minutes, Quiet Shift, compressor time
delay, deluxe defrost speed up capability. This section describes the
sequence of operation and trouble shooting methods for this control.
A05378
Fig. 10 – HK32EA003/008 Defrost Control
Quiet Shift (HK32EA003/008)
This control has the option of shutting down the compressor for 30
seconds going in and coming out of defrost. This is accomplished by
turning DIP switch 3 to the ON position. Factory default is in the OFF
position. Enabling this feature eliminates occasional noise complaints
associated with switching into and out of defrost.
Five-Minute Compressor Delay (HK32EA003/008)
This control features a 5-minute time delay to protect the compressor
from short cycling. The delay begins counting when the low voltage is
interrupted, and at the end of heating or cooling cycle.
System function and Sequence of operation
(HK32EA003/008)
On power-up (24 volts between R-C) the 5 minute cycle timer begins
counting down. The compressor will not be energized until this timer is
elapsed.
Cooling
On a call for cooling, thermostat makes R-O, R-Y, and R-G. Circuit R-O
energizes reversing valve switching it to cooling position. Circuit R-Y
sends low voltage through the safeties and energizes the T1 terminal on
the circuit board. If the compressor has been off for 5 minutes, or power
has not been cycled for 5 minutes, the OF2 relay and T2 terminal will
energize. This will close the contactor, start the outdoor fan motor and
compressor.
When the cycle is complete, R-Y is turned off and compressor and
outdoor fan should stop. When using Bryant thermostats, the reversing
valve remains energized in the cooling mode until the thermostat is
switched to heat, or the mode it turned off. The 5-minute time guard
begins counting. Compressor will not come on again until this time
delay expires. In the event of a power interruption, the time guard will
not allow another cycle for 5 minutes.
Heating
On a call for heating, thermostat makes R-Y, and R-G. Circuit R-Y sends
low voltage through the safeties and energizes the T1 terminal on the
circuit board. T1 energizes the defrost logic circuit. If the compressor
has been off for 5 minutes, or power has not been cycled for 5 minutes,
the OF2 relay and T2 terminal will energize. This will close the
contactor, start the outdoor fan motor and compressor.
When the cycle is complete, R-Y is turned off and the compressor and
outdoor fan should stop. The 5 minute time guard begins counting.
Compressor will not come on again until this time delay expires. In the
event of a power interruption, the time guard will not allow another
cycle for 5 minutes.
Defrost Sequence
The defrost control is a time/temperature control that has field selectable
settings of 30, 60, 90 and 120 minutes. These represent the amount of
time that must pass after closure of the defrost thermostat before the
defrost sequence begins.
The defrost thermostat senses coil temperature throughout the heating
cycle. When the coil temperature reaches the defrost thermostat setting
of approximately 32 degrees F, it will close, which energizes the DFT
terminal and begins the defrost timing sequence. When the DTF has
been energized for the selected time, the defrost cycle begins. If the
defrost thermostat opens before the timer expires, the timing sequence is
reset.
Defrost cycle is terminated when defrost thermostat opens (~65 degrees)
or automatically after 10 minutes.
Deluxe Defrost Speedup
To initiate a force defrost, speedup pins (J1) must be shorted with a flat
head screwdriver for 5 seconds and RELEASED. If the defrost
thermostat is open, a short defrost cycle will be observed (actual length
depends on Quiet Shift switch position). When Quiet Shift is off, only a
short 30 second defrost cycle is observed. With Quiet Shift ON, the
speed up sequence is one minute; 30 second compressor off period
followed by 30 seconds of defrost with compressor operation. When
returning to heating mode, the compressor will turn off for an additional
30 seconds and the fan for 40 seconds.
If the defrost thermostat is closed, a complete defrost cycle is initiated. If
the Quiet Shift switch is turned on, the compressor will be turned off for
two 30 second intervals as explained previously.
