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
diagnostic evaluations of the hardware to determine its con-
dition. 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 replac-
ing 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 breaker.
If the fuse is good, check for a shorted secondary of the
transformer or, if power is present to the module, replace the
module.
GREED LED (Labeled as COM) — These LEDs indicate
the communication status between different parts of the con-
troller and the network modules and should blink continu-
ously.
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 communication be-
tween the CCM and ISM is accomplished through the sen-
sor bus, which is a 3-wire cable.
2. If a green LED is on continuously, check the communi-
cation wiring. If a green LED is off, check the red LED
operation. If the red LED is normal, check the module
address switches (Fig. 36-38).
All system operating intelligence resides in the CVC. Some
safety shutdown logic resides in the ISM in case com-
munications 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 transformer located
in the module.
In the power panel, T1 supplies power to the compressor
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.
STAT
CONTRAST
BACK OF CVC
(CHILLER VISUAL
CONTROLLER)
J8
SERVICE
J5
KEYPAD
MODULE PART #
SOFTWARE PART #
J1
POWER/CCN
J7
SIO
Fig. 36 — Rear of CVC (Chiller Visual Controller)
80
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