Troubleshooting (HK32EA001)
If outdoor unit will not run:
1.Does the Y input has 24 volts from thermostat? If not, check thermostat or wire. If yes proceed to #2
2.The Y spade terminal on the circuit board should have 24 volts if Y input is energized. This output goes through the pressure switches and to the contactor. If 24 volts is present on the Y spade terminal, and the contactor is not closed, check voltage on contactor coil. If no voltage is present, check for opened pressure switch.
3.If voltage is present and contactor is open, contactor may be defective. Replace contactor if necessary.
4.If contactor is closed and unit will still not run, check wiring, capacitor and compressor
Defrost Speedup
To test the defrost function on these units, speed up pins are provided on the circuit board. To force a defrost cycle, the defrost thermostat must be closed, or the defrost thermostat pins must be jumpered. Follow the steps below to force a defrost cycle:
1.Jumper the DFT input
2.Short the speed up pins. This speeds up the defrost timer by a factor of 256. The longer the defrost interval setting, the longer the pins must be shorted to speed through the timing. For example, if interval is 90 min, the speed up will take (90/256)min x (60seconds /minute)= 21 seconds max. This could be shorter depending on how much time has elapsed since the defrost thermostat closed.
3.Remove the short immediately when the unit shifts into defrost. Failure to remove the short immediately will result in a very short forced defrost cycle (the 10 minute timer will be sped through in 2 seconds)
4.When defrost begins, it will continue until the defrost thermostat opens or 10 minutes has elapsed.
NOTE: The T1 terminal on the defrost board powers the defrost timing function. This terminal must be energized before any defrost function will occur.
If defrost thermostat is stuck closed:
Whether the unit is in heating or cooling mode, it will run a defrost cycle for 10 minutes each time the compressor has been energized for the selected time interval. The board will terminate automatically after 10 minutes of defrost time regardless of defrost thermostat position.
If defrost thermostat is stuck open:
The unit will not defrost
NOTE: Unit will remain in defrost until defrost thermostat reopens at approximately 65_F coil temperature at liquid line or remainder of defrost cycle time.
5.Turn off power to outdoor unit and reconnect fan-motor lead to OF2 on control board after above forced-defrost cycle.
If unit will not defrost:
1.Perform the speedup function as described above to test the defrost function of the circuit board.
2.If the unit does not go into defrost after performing the speed up, check for 24 volts on the T1 terminal. This terminal powers the defrost circuit, and must be energized before any defrost function can occur. The T1 should be energized once the Y terminal is energized and the pressure switches are closed. Ensure the T1 wire is connected at the contactor, and that 24 volts is present on the T1 spade terminal.
3.If all voltages are present and unit will still not run defrost, remove thermostat pigtail harness from board and perform checks directly on input pins with jumper wires. The pigtail may have a bad connection or be mis-wired.
To fully troubleshoot defrost thermostat and control function (HK32EA001):
1.Turn thermostat to OFF. Shut off all power to outdoor unit.
2.Remove control box cover for access to electrical components and defrost control board.
3.Disconnect defrost thermostat leads from control board, and connect to ohmmeter. Thermostat leads are black, insulated wires connected to DFT and R terminals on control board. Resistance reading may be zero (indicating closed defrost thermostat), or infinity (∞ for open thermostat) depending on outdoor temperature.
4.Jumper between DFT and R terminals on control board as shown in Fig. 10.
5.Disconnect outdoor fan motor lead from OF2. Tape lead to prevent grounding.
6.Turn on power to outdoor unit.
7.Restart unit in heating mode, allowing frost to accumulate on outdoor coil.
8.After a few minutes in heating mode, liquid line temperature at defrost thermostat should drop below closing set point of defrost thermostat of approximately 32_F. Check resistance across defrost thermostat leads using ohmmeter. Resistance of zero indicates defrost thermostat is closed and operating properly.
9.Short between the speed-up terminals using a thermostat screwdriver. This reduces the timing sequence to 1/256 of original time. (See Table 3.)
Table 3—Defrost Control Speed-Up Timing Sequence
| PARAMETER | MINIMUM | MAXIMUM | SPEED---UP |
| (MINUTES) | (MINUTES) | (NOMINAL) |
| |
| 30---minute cycle | 27 | 33 | 7 sec |
| 50---minute cycle | 45 | 55 | 12 sec |
| 90---minute cycle | 81 | 99 | 21 sec |
| 10---minute cycle | 9 | 11 | 2 sec |
| 5---minutes | 4.5 | 5.5 | 1 sec |
!CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage or improper operation.
Exercise extreme caution when shorting speed-up pins. If pins are accidentally shorted to other terminals, damage to the control board will occur.
10.Unit is now operating in defrost mode. Check between C and W2 using voltmeter. Reading on voltmeter should indicate 24v. This step ensures defrost relay contacts have closed, energizing supplemental heat (W2) and reversing valve solenoid (O).
11.Unit should remain in defrost no longer than 10 minutes. Actual time in defrost depends on how quickly speed-up jumper is removed. If it takes 2 sec to remove speed-up jumper after unit has switched to defrost, the unit will switch back to heat mode.
12.After a few minutes, in defrost (cooling) operation, liquid line should be warm enough to have caused defrost thermostat contacts to open. Check resistance across defrost thermostat. Ohmmeter should read infinite resistance, indicating defrost thermostat has opened at approximately 65_F.
13.Shut off unit power and reconnect fan lead.
