Service; Unbrazing System Components; Troubleshooting Geothermal Logic Ccm - Bard Q-TEC Series Literature Assembly

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.
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.
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
Manual 2100-738A
Page 62 of 71
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 37.)
The compressor logic control board has five LED lights
providing status updates of the system operation (see
Figure 38). 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