Installation guide
Table 5 - Model Plug
Model
Number
*CA724
*CA736
*CA748
*CA760
*CA924
*CA936
*CA948
*CA960
Model Plug
Number
HK70EZ040
HK70EZ042
HK70EZ044
HK70EZ046
HK70EZ009
HK70EZ011
HK70EZ013
HK70EZ015
Pin Resistance
(kOhms)
Pin 1-4 Pin 2-3
18 75
18 120
18 180
18 270
5.1 91
5.1 150
5.1 220
5.1 360
The model plug is used to identify the type and size of unit to the
control.
On new units, the model and serial numbers are input into the
board's memory at the factory. If a model plug is lost or missing at
initial installation, the unit wilt operate according to the information
input at the factory and the appropriate error code wilt flash
temporarily.
A FAST® Parts replacement board contains no model and serial
information. If the factory control board fails, the model plug must
be transferred from the original board to the replacement board
for the unit to operate.
NOTE: The model plug takes priority over factory model information
input at the factory. If the model plug is removed after initial power
up, the unit will operate according to the last valid model plug
installed, and flash the appropriate fault code temporarily.
Pressure Switch Protection
The outdoor unit is equipped with high and low pressure
switches.
If the control senses the opening of a high or low pressure switch,
it will respond as follows:
1. De-energize the appropriate compressor contactor.
2. Keep the outdoor fan operating for 15 minutes.
3. Display the appropriate fault code (see Table 6).
4. After a 15 minute delay, if there is still a call for cooling and
the LPS or HPS is reset, the appropriate compressor
contactor is energized.
5. If LPS or HPS has not closed after a 15 minute delay, the
outdoor fan is turned off. If the open switch closes anytime
after the 15 minute delay, then resume operation with a call
for cooling.
6. If LPS or HPS trips 3 consecutive cycles, the unit operation
is locked out for 4 hours.
7. In the event of a high pressure switch trip or high pressure
lockout, check the refrigerant charge outdoor fan operation
and outdoor coil for airflow restrictions.
8. In the event of a low pressure switch trip or low pressure
lockout, check the refrigerant charge and indoor airflow.
Control Fault
If the outdoor unit control board has failed, the control will flash
the appropriate fault code. (See Table 6) The control board
should be replaced.
Brown Out Protection
If the line voltage is less than 187v for at least 4 seconds, the
appropriate compressor contactor and fan relay are de-energized.
Compressor and fan operation are not allowed until voltage is a
minimum of 190v. The control will flash the appropriate fault code
(see Table 6)
230 V Brown Out Protection Defeated:
The brownout feature can be defeated if needed for severe noisy
power conditions. This defeat should always be a last resort to
solving the problem. Defeat can be initiated through the forced
421 01 1702 04
defrost pins as follows:
The brownout toggle is accomplished by shorting the defrost pins
from power up with the OAT and OCT sensor connector removed.
After 3 seconds, the status of the force defrost short and the
OAT/OCT as open will be checked. If correct, then the brownout
wilt be toggled.
• Status code 6 shows the brownout is disabled.
• Status code 5 shows the brownout is active.
After the brownout defeat is set, power down and reinstall the
OAT/OCT sensor and remove the short from the forced defrost
pins. As long as the short on the forced defrost remains, the OAT
and OCT faults will not be cleared. The code will continue to be
flashed.
The control is shipped with the brownout active. The change in
status is remembered until toggled to a new status. A power
down/power up sequence will not reset the status. It may be
necessary to do the toggle twice to cycle to the desired state of
the defeat.
230V Line (Power Disconnect) Detection
If there is no 230v at the compressor contactor(s) when the indoor
unit is powered and cooling demand exists, the appropriate error
code is displayed (see Table 6). Verify that the disconnect is
closed and 230v wiring is connected to the unit.
Compressor Voltage Sensing
The control board input terminals labeled VS and L2 (see Fig. 10)
are used to detect compressor voltage status, and alert the user
of potential problems. The control continuously monitors the high
voltage on the run capacitor of the compressor motor. Voltage
should be present any time the compressor contactor is
energized, and voltage should not be present when the contactor
is de-energized.
Contactor Shorted Detection
If there is compressor voltage sensed when there is no demand
for compressor operation, the contactor may be stuck closed or
there is a wiring error. The control will flash the appropriate fault
code.
Compressor Thermal Cutout
If the control senses the compressor voltage after start-up, and is
then absent for 10 consecutive seconds while cooling demand
exists, the thermal protector is open. The control de-energizes
the compressor contactor for 15 minutes, but continues to operate
the outdoor fan.
The control Status LED will flash the appropriate code shown in
Table 6. After 15 minutes, with a call for low or high stage cooling,
the compressor contactor is energized. If the thermal protector
has not reset, the outdoor fan is turned off. If the call for cooling
continues, the control will energize the compressor contactor
every 15 minutes. If the thermal protector closes, (at the next 15
minute interval check), the unit will resume operation. If the
thermal cutout trips for three consecutive cycles, then unit
operation is locked out for 4 hours and the appropriate fault code
is displayed.
No 230V at Compressor
If the compressor voltage is not sensed when the compressor
should be starting, the appropriate contactor may be stuck open
or there is a wiring error. The control will flash the appropriate fault
code. Check the contactor and control box wiring.
Troubleshooting units for proper switching
between low & high stages
Check the suction pressures at the service valves. Suction
pressure should be reduced by 3-10% when switching from low
to high capacity.
Specifications subject to change without notice. 9