Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Catalog No. 04-53500145-01
Printed in U.S.A.
Form 50PSW-4SI
Pg 42
11-21
Replaces: 50PSW-3SI
© 2021 Carrier
Table 12 —
Troubleshooting
FAULT
POSSIBLE CAUSE
SOLUTION
COMPRESSOR
DOES NOT
OPERATE
Power Supply Off
Apply power, close disconnect.
Blown Fuse
Replace fuse or reset circuit breaker. Check for correct fuses.
Broken or Loose Wires
Replace or tighten the wires. Check for loose or broken wires at compressor, capacitor, or
contactor.
Voltage Supply Low
If voltage is below minimum voltage specified on unit data plate, contact local power
company.
Controller
Set controller to “COOL” and lowest temperature setting, the unit should run in the cooling
mode (reversing valve energized). Set unit to “HEAT” and the highest temperature setting,
the unit should run in the heating mode. If the compressor does not run in all cases, the
controller could be miswired or faulty.To ensure miswired or faulty thermostat verify 24 volts
is available on the unit section low voltage terminal strip between “R” and “C,” “Y” and “C,”
and “O” and “C.” Replace the controller if defective.
Safety Controls
Reset the controller to “OFF.” After a few minutes turn to “COOL” or “HEAT.” If the
compressor runs, unit was off on one of the safety controls. (See problem for possible
causes)
Compressor Overload Open If the compressor is cool and the overload will not reset, replace compressor.
Compressor Motor
Grounded
Internal winding grounded to the compressor shell. Replace compressor. If compressor
burnout, install suction filter drier.
Compressor Windings Open After compressor has cooled, check continuity of the compressor windings. If the windings
are open, replace the compressor.
UNIT OFF ON
HIGH-PRESSURE
SWITCH
Discharge Pressure Too
High
In “COOLING” mode: SOURCE COIL - Lack of or inadequate water flow. Entering water
temperature too warm. Scaled or plugged condenser.
In “HEATING” mode: LOAD COIL - Lack of or inadequate water flow. Entering water
temperature too warm. Scaled or plugged load coil.
Refrigerant Charge
The unit is overcharged with refrigerant. Recover refrigerant, evacuate and recharge with
factory recommended charge.
High-pressure Switch
Check for defective or improperly calibrated high-pressure switch.
UNIT OFF ON
LOW-PRESSURE
SWITCH
Suction Pressure Too Low
In “COOLING” mode: LOAD COIL - Lack of or inadequate fluid flow. Entering water
temperature too cold. Scaled or plugged load coil.
In “HEATING” mode: SOURCE COIL - Lack of or inadequate fluid flow. Entering water
temperature too cold. Scaled or plugged source coil.
Refrigerant Charge
The unit is low on refrigerant. Check for refrigerant leak, repair, evacuate and recharge with
factory recommended charge.
Low-pressure Switch
Check for defective or improperly calibrated low-pressure switch.
UNIT SHORT
CYCLES
Unit Oversized
Recalculate heating and or cooling loads.
Wiring and Controls
Loose connections in the wiring or a defective compressor contactor.
Fluid Volume
Inadequate load side fluid volume.
INSUFFICIENT
COOLING OR
HEATING
Unit Undersized
Recalculate heating and or cooling loads. If excessive, possibly adding insulation and
shading will rectify the problem. Unit may be short of refrigerant.
Refrigerant Charge
Unit may be short on refrigerant charge.
Compressor
Check for defective compressor. If discharge is too low and suction pressure is too high,
compressor is not pumping properly. Replace compressor.
Reversing Valve
Defective reversing valve creating bypass of refrigerant from discharge to suction side of
compressor. Replace reversing valve.
Operating Pressures
Compare unit operating pressures to the pressure / temperature chart for the unit.
TXV
Check TXV (thermostatic expansion valve) for possible restriction or defect. Replace if
necessary.
Moisture, Noncondensables
The refrigerant system may be contaminated with moisture or noncondensables. Recover
refrigerant, evacuate and recharge with factory recommended charge. Note: a liquid line
drier may be required.
8733830974
Summary of Contents for Aquazone 50PSW025
Page 15: ...15 Fig 9 Unit Size 122 1 Phase Complete C Deluxe D Control Package DWG No 50PSW120000 Rev 3 ...
Page 17: ...17 Fig 11 Unit Sizes 122 1 Phase W2W Open Control Package DWG No 50PSW120001 Rev 4 ...
Page 21: ...21 Fig 15 Unit Size 122 240 420 3 Phase W2W Open Control Package DWG No 50PSW320001 Rev 3 ...
Page 36: ...36 Fig 22 W2W Open Control Board ...
Page 37: ...37 Fig 23 Unit Protection Module UPM Sequence Of Operation ...
