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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 defr
ost:
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
(MINUTES)
MAXIMUM
(MINUTES)
SPEED---UP
(NOMINAL)
30 --- minute cycle 27 33 7sec
50 --- minute cycle 45 55 12sec
90 --- minute cycle 81 99 21sec
10 --- minute cycle 9 11 2sec
5 --- minutes 4.5 5.5 1sec
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.
CAUTION
!
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.