Manual 2100-738C
Page
64 of 73
SERVICE
Unbrazing System Components
If the refrigerant charge is removed from a scroll-
equipped unit by bleeding the high side only, it is
sometimes possible for the scrolls to seal, preventing
pressure equalization through the compressor. This may
leave low side shell and suction line tubing pressurized.
If the brazing torch is then applied to the low side
while the low side shell and suction line contains
pressure, the pressurized refrigerant and oil mixture
could ignite when it escapes and contacts the brazing
flame. To prevent this occurrence, it is important to
check both the high and low side with manifold gauges
before unbrazing.
Troubleshooting Geothermal Logic
CCM
The Bard QW*S3D Series is equipped with a high
pressure switch, low pressure switch and flow switch.
The switches are all located in the condenser section
of the unit. Each switch has its own illuminated
diagnostic light, which provides the user an easy
solution for basic troubleshooting.
High Pressure Switch
(Terminals HP1 and HP2) Circuit will be proved
as “closed” prior to energizing A or CC terminals.
If pressure switch opens, compressor will go into
soft lockout mode and compressor operation will be
terminated; green fault light will be illuminated. Logic
control will then go through 5-minute delay on break
plus random start sequence. If no fault is found on
next run cycle, compressor will continue operation. If
fault reoccurs, a hard lockout will be initiated and fault
signal is sent to L terminal.
Low Pressure Switch
(Terminals LP1 and LP2) Circuit will be proved as
“closed” prior to energizing A or CC terminals. The
condition of the LP terminals will then be ignored for
the first 90 seconds after a demand for compressor
operation. Following this 90-second period, if pressure
switch opens, compressor will go into soft lockout
mode and compressor operation will be terminated;
orange fault light will be illuminated. The compressor
control board will then go through a 5-minute delay on
break plus random start sequence. If no fault is found
on next run cycle, compressor will continue operation.
If fault reoccurs, hard lockout will be initiated and the
fault signal is sent to the L terminal.
Flow Switch
(Terminals FS1 and FS2) Circuit will be proved as
“closed” prior to energizing CC terminal. If float switch
opens, compressor will go into soft lockout mode and
compressor operation will be terminated; red fault
light will be illuminated. Compressor logic control will
then go through 5-minute delay on break plus random
start sequence. If no fault is found on next run cycle,
compressor will continue operation. If fault reoccurs,
hard lockout will be initiated and fault signal is sent to
L terminal.
The flow type switch is located on the copper tube
located at the condenser coil, water out. When there is
a fault related to the flow switch, a red LED light will
give notice by illumination, indicating a fault condition
is present.
Logic Control Board
Three of the four switches have normally closed
contacts and one contact (CO = unused) has a
normally open contact. If any of the four switches
fault, their corresponding light will blink and initialize
a soft lockout of the compressor circuit. If recurrence
happens on the same cooling call cycle, a hard lockout
of the compressor circuit will occur requiring a manual
system reset (See
SEQUENCE OF OPERATION
on
page 40.)
The compressor logic control board has five LED lights
providing status updates of the system operation (see
Figure 41). When the green status light is blinking, this
is an indication that there is 24V power to the board.
Upon an alarm detection from one of the four safety
switches, there will be a blinking light indicating a
fault. The faults are as follows:
HP = Green fault illumination
LP = Orange fault illumination
FS = Red fault illumination
CO = Yellow fault illumination
WARNING
Both the high and low side of the scroll
compressor must be checked with manifold
gauges before unbrazing system components.
Failure to do so could cause pressurized
refrigerant and oil mixture to ignite if it escapes
and contacts the brazing flame causing
property damage, bodily harm or death.
