14.Remove jumper between DFT and R terminals. Reconnect defrost thermostat leads. Failure to remove jumper causes unit to switch to defrost every 30, 60, or 90 minutes and remain in defrost for full 10 minutes.
15.Replace control box cover. Restore power to unit.
If defrost thermostat does not check out following above items or incorrect calibration is suspected, check for defective thermostat as follows:
1.Follow items 1-5 above.
2.Route sensor or probe underneath coil (or other convenient location) using thermocouple temperature measuring device. Attach to liquid line near defrost thermostat. Insulate for more accurate reading.
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.
| T2 C | | | | | | | | OF1 |
O | C O | DFT | | | | | | OF2 |
R | T1 | | | | | | | | |
W | | | | | | | | | |
2 | | | | | | | | | |
Y | | | | | | | | | |
C | Y | | | | | | | | |
SPEEDUP | P1 | | | | | | | | |
J1 | P3 | INTERVALTIMER | 90 | 60 30 | 30 60 | 120 | | |
| DFT | | OFF | | QUIET SHIFT | ON | HK32EA003 | |
| | | | | | | | |
| Speedup | | | | | Quiet | Defrost interval | |
| Pins | | | | | Shift | DIP switches | |
| | | | | | | | | A05378 |
Fig. 10 – HK32EA003 Defrost Control
HK32EA003 Defrost Control
The HK32EA003 defrost control is used in all 223A and 223B Legacy Line 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.
Quiet Shift
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
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
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 or automatically after 10 minutes.
