Service Manual

52
TWO- STAGE *CA7, * CA9, *CH6,
*CH9
Application Guidelines
ICP designed and tested the two- stage air conditioner and
heat pump products with R- 410A refrigerant to operate at a
minimum outdoor operating ambient in cooling mode at
55_F (12.8_C) and the maximum outdoor operating ambient
in cooling is 125_F (51.6_C). The maximum outdoor
operating ambient in heating mode is 66_F (18.8_C).
Continuous operation in heating mode is approved to - 30_F
(- 34.4_C). Thermostat options for the two stage units are as
follows:
S C, Dx- , Dx+, R four- wire connections for
Communicating wall control.
S W,Y1,Y2, and O wire connections for standard,
non- communicating thermostat.
*CA7, *CA9, *CH6, and *CH9 units can run, and are
matched with, both Observer® communicating wall control
and non- communicating 2- stage indoor fan coils and
furnaces. Only unit combinations listed in the two- stage
specifications, technical support manuals, or
AHRIdirectory.org are recommended.
Line sets for two stage units are similar to the single stage
units. However, some restrictions may apply to specific
combinations in long line applications. Refer to the Split
System Long Line Applications Guidelines for further
information.
The Tennessee Valley Authority (TVA) requires that electric
strip heat have a lockout feature. This is achieved through
Observer® communicating wall control must be used on all
TVA approved units.
Model Plug
Each control board contains a model plug. The correct
model plug must be installed in order for the system to
operate properly. (See Table 14.)
The model plug is used to identify the type and size of unit
to the control. On *CH6 models, the model plug is also used
to determine the start sequence timing for each individual
model.
On new units, the model and serial numbers are inputted
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 will operate according to the
last valid model plug installed, and flash the appropriate
fault code temporarily.
Table 14—Model Plug Information
MODEL
NUMBER
MODEL PLUG
NUMBER
PIN RESISTANCE
(K- ohms)
Pins 1 - 4 Pins 2- 3
*CH624 HK70EZ041 18 91
*CH636 HK70EZ043 18 150
*CH648 HK70EZ045 18 220
*CH660 HK70EZ047 18 360
*CH924 HK70EZ010 5.1 120
*CH936 HK70EZ012 5.1 180
*CH948 HK70EZ014 5.1 270
*CH960 HK70EZ016 11 5.1
*CA924 HK70EZ009 5.1 91
*CA936 HK70EZ011 5.1 150
*CA948 HK70EZ013 5.1 220
*CA960 HK70EZ015 5.1 360
*CA624 HK70EZ040 18 75
*CA636 HK70EZ042 18 120
*CA648 HK70EZ044 18 180
*CA660 HK70EZ046 18 270
Airflow Selections for *CA7, *CA9, *CH6,
*CH9 Using Non- Communicating
Thermostats
Airflow Selection for FVM4 Fan Coils for *CA7, *CA9,
*CH6, *CH9 Using Non- Communicating
Thermostats
The FVM4 provides high- and low- stage blower operation
to match the capacities of compressor at high- and
low- stage. To select recommended airflow, refer to FVM4
Installation Instructions. The FVM4 utilizes an Easy Select
control board that allows the installing technician to select
proper airflows. For adjustments to control board, select
appropriate HP SIZE and CFM ADJUST setting. This fan
coil has an adjustable blower off delay factory set at 90 sec
for high- and low- stage blower operation.
For other combinations of equipment consult specifications,
technical support manuals, or AHRIdirectory.org.
GENERAL INFORMATION
Defrost
This control offers 5 possible defrost interval times: 30, 60,
90, 120 minutes, or AUTO.
With non- communicating thermostats, these are selected
by dip switches on the unit control board. With
Communicating thermostats, the Communicating control
wall control. The Communicating control selection overrides
the control board dip switch settings.
AUTO defrost adjusts the defrost interval time based on the
last defrost time as follows:
S When defrost time <3 minutes, the next defrost
interval=120 minutes.
S When defrost time 3- 5 minutes, the next defrost
interval=90 minutes.
S When defrost time 5- 7 minutes, the next defrost
interval=60 minutes.
S When defrost time >7 minutes, the next defrost
interval=30 minutes.