Water to Air Troubleshooting Tips

Water to Air Troubleshooting Tips
Water to Air
Troubleshooting Tips
Troubleshooting
Problem/Issue
Possible Cause
Actions and Corrections
Entire unit will not
run.
Power supply is off
Apply power and close disconnect.
Circuit breaker
reset circuit breaker.
Voltage supply low
If voltage is below minimum voltage specified on unit
data plate, contact local power company.
Thermostat
Set the fan to On. The fan should run. Set thermostat
to Cool and lowest temperature setting, the unit
should run in the cooling mode. Set unit to Heat and
the highest temperature setting, the unit should run in
the heating mode. If neither the blower nor
compressor run in all three cases, the thermostat
could be wired incorrectly or faulty. To ensure
correct wiring or faulty thermostat verify 24 volts is
available on the low voltage terminal strip between
"R" and "C", "Y" and "C", and, if in cooling mode, "O"
and "C". If the blower does not operate, verify 24
volts between terminals "G" and "C". Replace the
thermostat if defective.
Problem/Issue
Possible Cause
Actions and Corrections
Blower operates but
compressor does
not.
Wiring
Check for loose or broken wires at compressor,
capacitor, or contactor.
Safety controls
Check Smart Relay screen for faults.
Capacitor
Check capacitor and replace if defective.
Compressor
overload open
If the compressor has cooled down and the overload
will not reset, replace compressor.
Compressor motor
grounded
Internal winding grounded to the compressor shell.
Replace compressor. If compressor burnout has
occurred, install suction filter dryer.
Compressor
windings open
After compressor has cooled, check continuity of the
compressor windings. If the windings are open, replace
the compressor.
PLC reads High
Discharge pressure
Pressure Check Unit too high
Or HARD
LOCKOUT HI
PRESSURE
In Cooling mode, check:
•
Lack of or inadequate water flow
•
Entering water temperature too warm
•
Scaled or plugged condenser In Heating mode
check:
•
Lack of or inadequate air flow
•
Blower is inoperative, clogged filter or
restrictions in ductwork
Refrigerant charge
The unit is overcharged with refrigerant. Reclaim
refrigerant, evacuate and recharge with factory
recommended charge.
High pressure
Check for defective high pressure switch.
Problem/Issue
Possible Cause
Actions and Corrections
PLC reads: Low
Pressure Check
Unit, or HARD
LOCKOUT LOW
PSI.
Suction pressure
too low
In Cooling mode, check:
•
Lack of or inadequate air flow
•
Entering water temperature too cold
•
Blower is inoperative, clogged filter or
restrictions in ductwork In Heating mode check:
•
Lack of or inadequate water flow
•
Entering water temperature too cold
•
Scaled or plugged condenser Check
refrigerant charge.
Always charge to nameplate.
Refrigerant charge
The unit is low on refrigerant. Check for refrigerant
leaks. Repair, evacuate and recharge with factory
recommended charge.
Low pressure switch Check for defective low pressure switch.
Unit Short Cycles
Insufficient cooling
TXV Bulb may be
defective/severed,
TXV valve stuck
shut, or moisture in
the refrigerant
system
TXV bulb and TXV control diaphragm can be replaced
after removing the charge, replacing the control device
and bulb, and properly recharging the unit to nameplate
value.
Unit oversized
Recalculate heating and or cooling loads.
Thermostat
Thermostat may be installed near an area with too
much air movement. Relocate or adjust grills
Wiring and controls
Loose connections in the wiring or a defective
compressor contactor.
Unit undersized
Recalculate heating and or cooling loads. If excessive,
adding insulation and shading may possibly fix the
problem.
Reversing valve
Defective reversing valve creates a bypass of
refrigerant from discharge to suction side of
compressor. Replace reversing valve.
Problem/Issue
Possible Cause
Actions and Corrections
Insufficient heating
Loss of conditioned
air by leaks
Check for leaks in duct work or look for entering
ambient air through doors or windows.
Airflow
Lack of adequate air flow or improper distribution of
air. Replace dirty filter.
Refrigerant charge
Low refrigerant charge causing poor operation.
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 creates a bypass of refrigerant
from discharge to suction side of compressor. Replace
reversing valve.
Operating pressures
Compare unit operating pressures to a pressure /
temperature chart for the refrigerant used.
TXV
Check TXV for restriction or defect. Replace if
necessary.
Moisture,
noncondensables
The refrigerant system may be contaminated with
moisture or noncondensables. Reclaim refrigerant,
evacuate and recharge with factory recommended
charge.
NOTE: A liquid line dryer may be required.
Loss of conditioned
air by leaks
Check for leaks in duct work or entering ambient air
through doors or windows.
PLC Reads: HARD
LOCKOUT FLOW
SWITCH
Inadequate or no
water flow
Check for water flow. Check flow switch by
temporarily bypassing it. Make sure all air is purged
from lines. Make sure flow center is purged and
functional. Check for proper flow direction.
PLC Reads: HARD
LOCKOUT PAN
LEVEL
Pan level switch
Check condensate drain for blockage. Make sure
condensate drain is properly installed. Check Pan level
switch by temporarily bypassing it. Make sure unit is on
a level surface.
PLC Reads: HARD
LOCKOUT
CURRENT SENS
Current sensor
Refer to blower operates but compressor does not.
Check current sensor by temporarily bypassing it.
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