Amana VXC20 Series, Installation & Service Reference

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ComfortNet™ System
Overview
A ComfortNet inverter heating and air conditioning system
uses an indoor unit, outdoor unit and thermostat which digitally
communicate with one another via a two-way communica-
tions path. The thermostat sends commands to the indoor
and outdoor units. The thermostat may request and receive
information from both the indoor and outdoor units. This in-
formation may be displayed on the CTK04 thermostat. The
indoor and outdoor units also interact with one another. The
outdoor unit may send commands to or request information
from the indoor unit. This two-way digital communications
between the thermostat and subsystems (indoor/outdoor unit)
and between subsystems is the key to unlocking the benefits
and features of the ComfortNet system.
Two-way digital communications is accomplished using only
two wires. The thermostat needs 24 VAC for power. 4 wires
between the indoor unit and thermostat plus two wires be-
tween the indoor unit and outdoor unit are all that are required
to operate the system.
ComfortNet System Advanced Features
The ComfortNet™ system permits access to additional system
information, advanced set-up features, and advanced diag-
nostic/troubleshooting features. These advanced features are
organized into a menu structure. See the AIR CONDITIONER
ADVANCED FEATURES MENU section for the menu layout.
Directions to Air Conditioner Advanced Fea-
ture Menus
Press MENU, scroll down and press COMFORTNET USER
MENU . Enter the date code (password) when prompted. The
date code is printed on the back of the thermostat; or press
MENU > EQUIPMENT STATUS and scroll down to find the
date code. After you enter the password, select COMFORT-
NET USER MENU, answer YES to the following menu and
select AIR CONDITIONER to view the system menus.
Diagnostics
The air conditioner’s diagnostics menu provides access to the
most recent faults. The six most recent faults are displayed
on the first screen. Six additional faults are displayed under
fault history. Faults are stored in order from most recent to
least recent. Any consecutively repeated fault is stored a
maximum of three times. Example: A leak in the system, low
refrigerant charge or an incompletely open stop valve can
cause the unit to flash error code E15. This error code sug -
gests that the unit is experiencing operation at low pressure.
The control will only store this fault the first three
consecutive
times the fault occurs.
NOTE: It is highly recommended that the fault list be cleared
after performing maintenance or servicing the air handler.
Status
This menu displays information about the systems current
status. This menu can be utilized to confirm correct function -
ality of the equipment and for troubleshooting purposes. The
following items will be displayed:
TS Time Stamp
MD
Mode
CRM Compressor Reduction Mode
RAD Requested and Actual % Demand
RAF Requested and Reported ID CFM
ATOF*
Outdoor Air Temperature
and Outdoor Fan RPM
DCT
Discharge Temperature
and Outdoor Coil Temperature
DLT Outdoor Liquid Temperature
PSDST**
Pressure Sensor and Outdoor
Suction Temperature
* Only for AVXC200**1AB or later revision.
ATPRM is shown in AVXC200**1AB or later revision.
** Only for AVXC200**1AB or later revision.
PSD is shown in AVXC200**1AA revision.
Time Stamp: Provides compressor run time in hours.
Mode: Current system operational mode (COOLING, COOL-
ING STARTUP, OIL RETURN, STOP).
Compressor Reduction Mode: The compressor is running
at a speed lower than what is requested, based on the cool-
ing load.
Requested and Actual % Demand: Compares the request-
ed cooling demand to what the equipment is providing. For
steady state operation, these number should match.
Requested and Reported ID CFM:
Compares the requested
indoor airflow to what the indoor equipment has reported.
Outdoor Air Temperature and Outdoor Fan RPM: Displays
the outdoor air temperature as well as the outdoor fan speed
(RPM).
Discharge Temperature and Outdoor Coil Temperature:
Displays the discharge temperature and outdoor coil tem-
perature sensor readings.
Outdoor Liquid Temperature: Displays liquid temperature
sensor readings.
Pressure Sensor: Displays the pressure sensor reading.
NOTE: Oil Return Mode:
In order to properly return oil to
the compressor, compressor speed may periodically adjust
to assist oil circulation.
Equipment Test
The mandatory system verification test is enabled from this
menu, which enables a functional check of the equipment, in
addition to ensuring proper stop valve position.