Adjusting System Charge - Wolf Steel Condo Pack Installation And Operating Instructions Manual

High head pressure;
Normal suction
pressure
WARNING!
FAULT CONDITION
Low head pressure;
Unit will not operate
High suction
pressure
Low suction
pressure;
Compressor cool;
Ice on indoor coil
High suction
Outdoor fan on;
pressure;
Compressor off
or �luctuating head
and suction
pressures
Pulsing noise at
expansion device or
Too little cooling
liquid line
Registers sweat
7.3

ADJUSTING SYSTEM CHARGE

Units come from the factory charged with the correct amount of refrigerant. There are times, however, when
the charge may need to be adjusted. Refrigerant leaks and addition of system components for servicing or
monitoring, for example, will require that the refrigerant charge be adjusted for the unit to function as intended.
Note that only qualified HVAC technicians shall adjust the charge.
Procedure:
Compressor
1� Operate the unit at standard AHRI conditions as close as possible (80°F DB / 67°F WB Indoor,
operates in short
95°F DB Outdoor).
cycles
2� Connect charging hose from liquid port on the refrigerant bottle to charging service port.
3� Open refrigerant bottle and purge hose at bottle fitting.
4� Temporarily install a temperature measuring device on the liquid line near the TXV and one at the
suction line near the compressor. Ensure that the temperature measuring device makes adequate
High head pressure;
contact and insulated for accurate readings.
Low suction
5. Operate the system for at least 10 minutes.
pressure
6� Check sub-cooling and superheat. Systems using thermostatic expansion valves should have a
sub-cooling as per its nameplate, if explicitly stated, or 7.5°F +/- 1°F otherwise. Superheat should
be 7°F to 9°F.
High head pressure;
i� If sub-cooling and superheat are low, adjust the TXV to 7°F to 9°F superheat.
Normal suction
ii� If sub-cooling is low and superheat is high or normal, add charge to obtain the required sub-
pressure
iii� If sub-cooling and superheat are high, adjust the TXV to 7°F to 9°F superheat.
iv� If sub-cooling is high or normal and superheat is low, remove charge to lower
Low head pressure;
High suction
pressure
Dirty outdoor coil
Refrigerant overcharge
THIS TROUBLESHOOTING GUIDE IS INTENDED FOR USE BY
Outdoor fan not running
QUALIFIED SERVICE PERSONNEL ONLY!
Air or non-condensables in system
POSSIBLE CAUSE
Expansion device stuck in open position
Power disconnected or loose connection
Defective compressor valves
Blown fuse / breaker tripped
Thermostat out of calibration is set too high
Low indoor airflow
Contactor defective
Operating below 65degF outdoors
Transformer defective
Moisture in system
High pressure control open (if provided)
Excessive load
Run or start capacitor defective
Defective compressor
Start relay defective
TXV hunting
Loose wire
Air or non-condensibles in system
Compressor stuck, grounded or open motor
winding, open internal overload
Air or non-condensibles in system
Low voltage condition
Improperly sized unit
Low indoor airflow
Improper indoor airflow
Incorrect refrigerant charge
Air, non-condensables or moisture in
system
Incorrect voltage
Defective overload protector
Refrigerant undercharge
Restriction in liquid line, expansion device
or filter drier
Lack of sufficient indoor airflow
Dirty outdoor coil
Refrigerant overcharge
cooling.
Outdoor fan not running
Air or non-condensables in system
the required sub-cooling.
Expansion device stuck in open position
Defective compressor valves
Clean coil
Correct system charge
Repair or replace
Recover refrigerant, evacuate and recharge
CORRECTION
Replace expansion device
Check voltage at contactor in condensing unit
Replace compressor
Replace fuses / reset breaker
Reset
Increase speed of blower or reduce restriction –
replace air filter
Check for 24VAC at contactor coil, replace if open
Add low ambient kit
Check wiring – replace transformer
Recover refrigerant – evacuate and recharge –
Reset – see high pressure correction (high pressure
replace filter drier
control opens at 600 psig)
Recheck load calculation
Replace
Replace
Replace
Check TXV bulb clamp – check air distribution on
Check for correct voltage at compressor – check coil – replace TXV
and tighten all connections
Recover refrigerant, evacuate and recharge
Wait at least 2 hours for overload to reset; if still
open, replace the compressor
Recover refrigerant, evacuate and recharge
Add start kit components
Recalculate load
Increase speed of blower or reduce restriction –
Check-should be approximately 400 CFM per ton
Charge per procedure in installation manual
Recover refrigerant
At compressor terminals, voltage must be +/10% of
nameplate marking when unit is operating
Replace – check for correct voltage
Add refrigerant
Remove or replace defective component
Clean/check filters, registers, or evaporator coil
that may cause a restriction.
Clean coil
Correct system charge
Repair or replace
Recover refrigerant, evacuate and recharge
Replace expansion device
Replace compressor
53
TABLE 6. CONT.
IOM
W415-1307 / B / 03.31.2017