Allied A80US2VX - Unit Components; Control Box

508033-02Issue 2135Page 6 of 48
Unit Components
A80US2VX unit components are shown in Figure 1.
The gas valve, combustion air inducer and burners can
be accessed by removing the access panel. Electrical
components are in the control box (Figure 2) found in the
blower section.
A80US2VX units are factory equipped with a bottom
return air panel in place. The panel is designed to be eld
removed as required for bottom air return. Markings are
provided for side return air and may be cut out in the eld.
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
Electrostatic discharge can a󰀨ect electronic components.
Take precautions during furnace installation and service
to protect the furnace’s electronic controls. Precautions
will help to avoid control exposure to electrostatic
discharge by putting the furnace, the control and the
technician at the same electrostatic potential. Neutralize
electrostatic charge by touching hand and all tools on
an unpainted unit surface, such as the gas valve or
blower deck, before performing any service procedure.
CAUTION
Control Box
Control Transformer (T1)
A transformer located in the control box provides power
tothe low voltage section of the unit. Transformers on
allmodels are rated 40VA with a 120V primary and a 24V
secondary.
Door Interlock Switch (S51)
A door interlock switch rated 14A at 125VAC is wired in
series with line voltage. When the inner blower access
panel is removed the unit will shut down.
CONTROL BOX
Transformer
SureLight
®
Integrated Control
Interlock Switch
Circuit Breaker
Figure 2.
Circuit Breaker (CB8)
A 24V circuit breaker is also located in the control box. The
switch provides overcurrent protection to the transformer
(T1). The breaker is rated 3A at 32V. If the current exceeds
this limit the breaker will trip and all unit operation will
shutdown. The breaker can be manually reset by pressing
the button on the face. See Figure 3.
CIRCUIT BREAKER CB8
PRESS TO RESET
Figure 3.
Shock hazard.
Disconnect power before servicing.
Integrated control is not eld repairable. If
control is inoperable, simply replace entire
control. Can cause injury or death. Unsafe
operation will resul if repair is attempted.
WARNING
Integrated Control (A92)
Units are equipped with the Comfort Sync
®
enabled
SureLight
®
two-stage, variable speed integrated control.
This control is used with the Comfort Sync
®
Wi-Fi
®
thermostat as part of a communicating comfort system.
The control can also operate with a non-communicating
conventional single or two-stage thermostat. The system
consists of a ignition / blower control (Figure 4 and Figure
5) with control pin designations in Table 1, Table 2 and
Table 3 and ignitor (Figure 13). The control and ignitor
work in combination to ensure furnace ignition and ignitor
durability. The control provides gas ignition, safety checks
and indoor blower control with two-stage gas heating.
The furnace combustion air inducer, gas valve and indoor
blower are controlled in response to various system inputs
such as thermostat signal, pressure and limit switch signal
and ame signal. The control features a seven-segment
LED display, indicating furnace status (including indoor
blower) and error codes. The LED ashes in single digits.
For example using Table 5 under LIMIT CODE, an “E”
followed by “2” followed by “5” followed by “0”, the limit
switch circuit is open. The control also has two unpowered
(dry) 1/4” contacts for a humidier and a 120 volt accessory
terminal. Both rated at (1) one amp each.