Installation guide

and finish of the defrost cycle. For installations using a
standard 2-stage thermostat, this feature must be enabled
by selecting the 3rd position dip switch on the outdoor control
board. For installations using an Observer Wall Control, it
must be enabled at the Wall Control. When activated, the
following sequence of operation occurs:
Defrost Initiation - the compressor is de-energized for 70
seconds. During this 70 second compressor off time, the
reversing valve will be energized. Once the 70 second
compressor off time has been reached, the compressor will
be energized then the outdoor fan will be de-energized at
which time the normal defrost cycle begins.
Defrost Termination - The outdoor fan will be energized
shortly before the compressor is de-energized for 60
seconds. During the compressor 60 second off time, the
reversing valve will be de-energized. Once the 60 second
compressor off time has been completed, the compressor will
be energized at which time the system will be in normal heat
mode.
Liquid-Line Accessory
In heat pump long-line applications, a liquid-line solenoid is
required to control refrigerant migration in the heating mode.
The solenoid should be installed near the outdoor unit with
the arrow facing the outdoor unit. This is the direction of flow
control. See application manual for long-line application
details.
Accessory Liquid Solenoid with Observer Communicating
Wall Control: When using the Observer Wall Control, the
liquid-line solenoid output is provided at the Y1 connection.
Connect the solenoid as shown in the wiring label diagram.
This is a 24vac output that is energized whenever the
compressor is energized. It closes, in the compressor off
mode, to prevent refrigerant migration into the unit through
the liquid-line.
On Systems with Accessory Liquid Solenoid Using a
Non-Communicating Thermostat: The liquid solenoid is
connected to the Y1 and C terminal connections. The liquid
solenoid closes, in the compressor off mode, to prevent
refrigerant migration into the unit through the liquid-line.
TROUBLESHOOTING
If the compressor fails to operate with a cooling call, Table 4
can be used to verify if there is any damage to the
compressor windings causing system malfunction.
Table 4 - Winding Resistance
Winding Resistance At 70°F +/- 20°F
(21,11°O +/- 11,11°O)
Winding 24 36 48 60
Start
(S-C) 1.64 1.52 1.86 1.63
Run
(R-C) 1.30 0.88 0.52 0.39
Systems Communication Failure
If communication with the Observer Communicating Wall
Control will flash the appropriate fault code. (See Table 6)
Check the wiring to the wall control, indoor and outdoor units.
Model Plug
Each control board contains a model plug. The correct model
plug must be installed for or the system to operate properly
(see Table 5).
428 01 1703 02
Model
Number
*CH624
*CH636
*CH648
*CH660
*CH924
*CH936
*CH948
*CH960
Table 5 - Model Plug
Pin Resistance
Model Plug
Number
HK70EZ041
HK70EZ043
HK70EZ045
HK70EZ047
HK7OEZ010
HK70EZ012
HK70EZ014
HK70EZ016
(kOhms)
Pin 1-4 Pin 2-3
18 91
18 150
18 220
18 360
5.1 120
5.1 180
5.1 270
11 5.1
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 will operate according to
the information input at the factory and the appropriate error
code will 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 wilt 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 wilt
flash the appropriate fault code. (See Table 6) The control
board should be replaced.
Brown Out Protection
If the line voltage is tess 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
Specifications subject to change without notice. 11