CVH8, HVH8, TVH8, VA9, HVA9, TVA9: APPLICATION GUIDELINE & SERVICE MANUAL
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
37
The service valve cannot be field repaired; therefore, only a complete
valve or valve stem and service-port caps are available for replacement.
If the service valve is to be replaced, a metal barrier must be inserted
between the valve and the unit to prevent damaging the unit exterior
from the heat of the brazing operations.
Pumpdown & Evacuation
If this system requires either a Pump Down or Evacuation for any
reason, the procedures below must be followed:
Pump Down –*VH8
Because this system has an inverter controlled compressor, suction
pressure transducer and EXV, conventional procedure cannot be used to
“pump down” and isolate the refrigerant into the outdoor unit. This
procedure can only be used in the cooling mode operation.
1. Connect gauges to *VH8 liquid and vapor service valve ports to
monitor operating pressures during and at completion of the
procedure.
2. Force system to operate in high stage by creating a large differential
between room temperature and set point on thermostat. Use
multi-meter to verify that 24 VAC is present between C and Y1 and
Y2 terminals at outdoor unit.
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 heat pump 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.
Pump Down - *VA9
Because this system has an inverter controlled compressor, suction
pressure transducer, conventional procedure cannot be used to “pump
down” and isolate the refrigerant into the outdoor unit. This procedure
can only be used in the cooling mode operation.
1. Connect gauges to *VA9 liquid and vapor service valve ports to
monitor operating pressures during and at completion of the
procedure.
2. Force system to operate in high stage by creating a large differential
between room temperature and set point on thermostat. Use
multi-meter to verify that 24 VAC is present between C and Y1 and
Y2 terminals at outdoor unit.
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 *VH8
Refrigerant recovery and evacuation can be performed, 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 *VH8 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. Allow extra time for refrigerant
recovery and establishing a thorough evacuation.
Evacuation and recovery of refrigerant from *VA9
1. Connect gauges to *VA9 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.
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. 40 and Fig. 41 show test points (TP) on reversing
valve for recording temperatures. Insulate points for more accurate
reading.
If valve is defective:
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.
CAUTION
!
PERSONAL INJURY HAZARD
Failure to follow this caution may result in personal injury.
Wear safety glasses, protective clothing, and gloves when handling
refrigerant.
CAUTION
!
ENVIRONMENTAL HAZARD
Failure to follow this caution may result in environmental damage.
Federal regulations require that you do not vent refrigerant to the
atmosphere. Recover during system repair or final unit disposal.
To Next Page
Loading...