Control Module Communication; Alert Code T415-418; Communication Failures; Red Led - Carrier 48/50PG C03-14 Operation And Service Manual

Alert Code T415 − IAQ Input Out of Range
This alert occurs when the IAQ input (on ECB) is less than 3.5 mA
and the sensor is configured as installed. IAQ operation will be
disabled. Check sensor and wiring. This alert clears automatically.
Alert Code T416 − OAQ Input Out of Range
This alert occurs when the OAQ input (on ECB) is less than 3.5
mA and the sensor is configured as installed. OAQ operation will
be disabled. Check sensor and wiring. This alert clears
automatically.
Alert Code T418
There are 4 different alerts under this one alert code. Pressing enter
and esc on the marquee or navigator to expand the T418 alert will
show you one of the below alerts. All these alerts are generated by
the OAU device and reported to the MBB. These alerts can only
occur if the Outdoor Air Unit Type (Configuration → OAU →
OA.TY) is not set to 0. Control action is only taken on the OAU
side and these alerts will reset automatically when the OAU clears
them. Refer to the EnergyXv2 Supplement Installation
Instructions for more information on these alarms.
OAU Motor Failure
This alert occurs when the OAU Motor Failure Alarm (Operating
Modes → OAU → ALM.1) is on. This is usually due to motor
status reporting a failure on the OAU.
OAU Dirty Filter
This alert occurs when the OAU Dirty Filter Alarm (Operating
Modes → OAU → ALM.2) is on. This is usually due to filter
status reporting a dirty filter on the OAU.
OAU Low CFM
This alert occurs when the OAU Low CFM Alarm (Operating
Modes → OAU → ALM.3) is on. This is usually due to OAU not
capable of achieving proper CFM.
OAU General Alarm
This alert occurs when the OAU Alarm (Operating Modes →
OAU → ALM.4) is on. Refer to the specific OAU documentation
for details.
Table 13 – LEN and CCN Communication Resistances
Ω Ω
Ω Ω
Ω Ω
Ω Ω

Control Module Communication

Red LED

Proper operation of the MBB and ECB control boards can be
visually checked by looking at the red status LEDs. When
operating correctly, the red status LEDs should blink in unison at a
rate of once every 2 seconds. If the red LED on the ECB is not
blinking, check the DIP switch positions on the board. If the red
LEDs are not blinking in unison, verify that correct power is being
supplied to all modules. A blinking red LED at the rate of once per
second means that software is not loaded on the board. Also, be
sure that the board is supplied with the current software. If
necessary, reload current software. A board LED that is lit
continuously should be replaced.

Green LED

The MBB and ECB each have one green LED. The Local
Equipment Network (LEN) LED should always be blinking
whenever power is on. If LEN LED is not blinking, check LEN
connections for potential communication errors (MBB J3, J4, and
J5). Communication between modules is accomplished by a 3-wire
sensor bus. These 3 wires run in parallel from module to module.
The J4 connector on the MBB also provides both power and
communication directly to the Scrolling Marquee display. The J5
connector on the MBB provides a LEN interface at the field
connection terminal (TB).
Yellow LED
The MBB has one yellow LED which is used to indicate CCN
communication activity. The Carrier Comfort Network (CCN)
LED will blink during times of network communication.

Communication Failures

If the Scrolling Marquee or Navigator display Communication
Failure or the green or yellow LED's do not flash on the boards
then the problem could be the communication chip on one of the
control boards (MBB or ECB). Disconnect all the LEN and CCN
plugs from the board and use an ohm meter to measure the
resistance on the communication pins of the boards to determine if
the board is bad. If the reading is less than half the value indicated
in Table 13, then the board needs to be replaced.
NOTE: The resistive values should be read when the board is
powered off and the unit is locked out.
Ω Ω
Ω Ω
Ω
Ω
44
Ω Ω
Ω Ω