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3. Close the liquid service valve.
4. The unit will continue to run until high or low pressure
switches open. Close vapor service valve once compressor
shuts down.
5. Remove power from indoor and outdoor unit prior to
servicing unit.
6. A quantity of charge will remain in isolated section of
system dependent on ambient temperature and overall
system charge. This charge must be manually recovered. A
recovery system will be required to remove final quantity of
refrigerant from indoor coil and line set.
Evacuation and recovery of refrigerant from 288BNV
Because this system has an EXV for the heating expansion device,
additional steps may be taken to open the EXV for fastest
refrigerant recovery and evacuation. If the EXV is not open when
pulling a vacuum or recovering refrigerant from the heat pump
unit, extended evacuation time may be required and/or inadequate
vacuum obtained. The UI (User Interface) has provisions to open
the EXV for refrigerant recovery and/or evacuation.
1. Connect gauges to 288BNV liquid and vapor service valve
ports to monitor operating pressures during and at comple-
tion of the procedure. Attach recovery system or vacuum
pump to gauge set as needed for the service procedure. The
service valves must be open to evacuate the unit through the
line set service ports. The suction capillary service port is a
direct connection to the suction port of the compressor and
may also be used.
2. In the advanced menu of the UI, go to Checkout > Heat
Pump > Evacuation.
3. Set desired time period. Default time period for the proced-
ure is 120 minutes.
4. Select START on UI to open the valve.
5. Begin evacuation or refrigerant recovery as required for the
procedure after UI indicates the EXV is open. Power may
be removed from heat pump after the UI indicates "READY
TO EVACUATE."
6. Remove power from indoor and heat pump unit prior to ser-
vicing unit. The EXV will retain the open position.
NOTE: See service training materials for troubleshooting the EXV
using EXV CHECK mode.
Evacuation and recovery of refrigerant from 288BNV
when using non- - communicating thermostat
Refrigerant recovery and evacuation can be performed without a
UI (User Interface) but will take more time. If EXV is not forced
open the recovery and evacuation must rely on check valve as a
bypass.
1. Connect gauges to 288BNV liquid and vapor service valve
ports to monitor operating pressures during and at
completion of the procedure. Attach recovery system or
vacuum pump to gauge set as needed for the service
procedure. The service valves must be open to evacuate the
unit through the line set service ports. The suction capillary
service port is a direct connection to the suction port of the
compressor and may also be used.
2. Begin evacuation or refrigerant.
refrigerant recovery and establishing a thorough evacuation.
Evacuation and recovery of refrigerant from 189BNV
Evacuation and recovery of refrigerant from 189BNV
when using non- - communicating thermostat
Reversing Valve
In heat pumps, changeover between heating and cooling modes is
accomplished with a valve that reverses flow of refrigerant in
system. This reversing valve device is easy to troubleshoot and
replace. The reversing valve solenoid can be checked with power
off with an ohmmeter. Check for continuity and shorting to
ground. With control circuit (24v) power on, check for correct
voltage at solenoid coil. Check for overheated solenoid.
With unit operating, other items can be checked, such as frost or
condensate water on refrigerant lines.
The sound made by a reversing valve as it begins or ends defrost is
a "whooshing" sound, as the valve reverses and pressures in system
equalize. An experienced service technician detects this sound and
uses it as a valuable troubleshooting tool.
Using a remote measuring device, check inlet and outlet line
temperatures. DO NOT touch lines. If reversing valve is operating
normally, inlet and outlet temperatures on appropriate lines should
be close to each other. Any difference would be due to heat loss or
gain across valve body. Temperatures are best checked with a
remote reading electronic- -type thermometer with multiple probes.
Route thermocouple leads to inside of coil area through service
valve mounting plate area underneath coil. Fig. 48 and Fig. 49
show test points (TP) on reversing valve for recording
temperatures. Insulate points for more accurate reading.
If valve is defective:
Allow extra time for
41
1. Connect gauges to 189BNV liquid and vapor service valve
ports to monitor operating pressures during and at comple-
tion of the procedure. Attach recovery system or vacuum
pump to gauge set as needed for the service procedure. The
service valves must be open to evacuate the unit through the
line set service ports.
1. Connect gauges to 189BNV liquid and vapor service valve
ports to monitor operating pressures during and at
completion of the procedure. Attach recovery system or
vacuum pump to gauge set as needed for the service
procedure. The service valves must be open to evacuate the
unit through the line set service ports.
1. Shut off all power to unit and remove charge from system.
2. Remove solenoid coil from valve body. Remove valve by
cutting it from system with tubing cutter. Repair person
should cut in such a way that stubs can be easily re- -brazed
back into system. Do not use hacksaw. This introduces
chips into system that cause failure. After defective valve is
removed, wrap it in wet rag and carefully unbraze stubs.
Save stubs for future use. Because defective valve is not
overheated, it can be analyzed for cause of failure when it is
returned.
3. Braze new valve onto used stubs. Keep stubs oriented
correctly. Scratch corresponding matching marks on old
valve and stubs and on new valve body to aid in lining up
new valve properly. When brazing stubs into valve, protect
valve body with wet rag to prevent overheating.
4. Use slip couplings to install new valve with stubs back into
system. Even if stubs are long, wrap valve with a wet rag to
prevent overheating.
5. After valve is brazed in, check for leaks. Evacuate and
charge system. Operate system in both modes several times
to be sure valve functions properly.
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