Control Modules; Red Led (Labeled As Stat); Green Led (Labeled As Com); Notes On Module Operation - Carrier 23xl Start-Up, Operation And Maintenance Instructions Manual

Control Modules —
Turn controller power off before
servicing controls. This ensures safety and prevents damage to
the controller.
The CVC, CCM, and ISM modules perform continuous di-
agnostic evaluations of the hardware to determine its condition.
Proper operation of all modules is indicated by LEDs (light-
emitting diodes) located on the circuit board of the CVC,
CCM, and ISM.
There is one green LED located on the CCM and ISM
boards respectively, and one red LED located on the CVC,
CCM, and ISM boards respectively.
RED LED (Labeled as STAT) — If the red LED:
• blinks continuously at a 2-second interval, the module is
operating properly
• is lit continuously, there is a problem that requires
replacing the module
• is off continuously, the power should be checked
• blinks 3 times per second, a software error has been dis-
covered and the module must be replaced
If there is no input power, check the fuses and circuit break-
er. If the fuse is good, check for a shorted secondary of the
transformer or, if power is present to the module, replace the
module.
GREEN LED (Labeled as COM) — These LEDs indicate
the communication status between different parts of the con-
troller and the network modules and should blink continuously.
J1
J5
KEYPAD POWER/CCN
STAT
CONTRAST BACK OF CVC
(CHILLER VISUAL
CONTROLLER)
MODULE PART #
J7
SIO SOFTWARE PART #
J8
SERVICE
Fig. 42 — Rear of CVC (Chiller Visual Controller)

Notes on Module Operation

1. The chiller operator monitors and modifies configura-
tions in the microprocessor by using the 4 softkeys and
the CVC. Communications between the CVC and the
CCM is accomplished through the SIO (Sensor Input/
Output) bus, which is a phone cable. The communica-
tion between the CCM and ISM is accomplished
through the sensor bus, which is a 3-wire cable.
2. If a green LED is on continuously, check the commu-
nication wiring. If a green LED is off, check the red
LED operation. If the red LED is normal, check the
module address switches (Fig. 42-44).
All system operating intelligence resides in the CVC.
Some safety shutdown logic resides in the ISM in case
communications are lost between the ISM and CVC.
Outputs are controlled by the CCM and ISM as well.
3. Power is supplied to the modules within the control
panel via 24-vac power sources.
The transformers are located within the power panel,
with the exception of the ISM, which operates from a
115-vac power source and has its own 24-vac trans-
former located in the module.
In the power panel, T1 supplies power to the compres-
sor oil heater, oil pump, and optional hot gas bypass,
and T2 supplies power to both the CVC and CCM.
Power is connected to Plug J1 on each module.
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