FHP EV Series Installation And Maintenance Manual - page 11
EV SERIES
11
PROBLEM
ENTIRE UNIT DOES
NOT RUN
BLOWER OPERATES
BUT COMPRESSOR
DOES NOT
UNIT OFF ON
HIGH PRESSURE
CONTROL
UNIT OFF ON
LOW PRESSURE
CONTROL
UNIT SHORT
CYCLES
INSUFFICIENT
COOLING OR
HEATING
POSSIBLE CAUSE
Power supply off
Blown fuse
Broken or loose wires
Voltage supply low
Thermostat
Thermostat
Wiring
Safety controls
Compressor overload open
Compressor motor grounded
Compressor windings open
Discharge pressure too high
Refrigerant charge
High pressure switch
Suction pressure too low
Refrigerant charge
Low pressure switch
Unit oversized
Thermostat
Wiring and controls
Unit undersized
Loss of conditioned air
by leaks
Airflow
Refrigerant charge
Compressor
Reversing valve
Operating pressures
TXV
Moisture, noncondensables
CHECKS AND CORRECTIONS
Apply power, close disconnect.
Replace fuse or reset circuit breaker. Check for correct fuses.
Replace or tighten the wires.
If voltage is below minimum voltage specified on unit data plate, contact local power company.
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 (reversing valve energized). Set unit to "HEAT" and
the highest temperature setting, the unit should run in the heating mode. If neither the blower or
compressor run in all three cases, the thermostat could be miswired or faulty. To ensure miswired
or faulty thermostat verify 24 volts is available on the condensing section low voltage terminal strip
between "R" and "C", "G" and "C", "Y" and "C", and “O” and “C” (cooling only). Replace the
thermostat if defective.
Check setting, calibration, and wiring.
Check for lose or broken wires at compressor, capacitor, or contactor.
Check CCMI board red fault L.E.D. for blink code (See problem for possible causes)
If the compressor is cool and the overload will not reset, replace compressor *.
Internal winding grounded to the compressor shell. Replace compressor and liquid line
drier. If compressor burnout, install suction drier.
After compressor has cooled, check continuity of the compressor windings. If the
windings are open, replace the compressor and liquid line drier.
In "COOLING" mode: Lack of or inadequate water flow. Entering water temperature too
warm. Scaled or plugged condenser.
In “HEATING” mode: Lack of or inadequate air flow. Entering air temperature too warm.
Blower inoperative, clogged filter, or restrictions in ductwork.
The unit is overcharged with refrigerant. Reclaim refrigerant, evacuate and recharge with
factory recommended charge.
Check for defective or improperly calibrated high-pressure switch.
In "COOLING" mode: Lack of or inadequate air flow. Entering air temperature too cold.
Blower inoperative, clogged filter, or restrictions in ductwork.
In "HEATING" mode: Lack of or inadequate water flow. Entering water temperature too
warm. Scaled or plugged condenser.
The unit is low on refrigerant. Check for refrigerant leak, repair, evacuate and recharge
with factory recommended charge.
Check for defective or improperly calibrated low-pressure switch.
Recalculate heating and or cooling loads.
Thermostat installed near a supply air grill, relocate thermostat. Readjust heat anticipator.
Loose connections in the wiring or a defective compressor contactor.
Recalculate heating and or cooling loads. If excessive, possibly adding insulation and
shading will rectify the problem.
Check for leaks in duct work or introduction of ambient air through doors or windows.
Lack of adequate air flow or improper distribution of air. Replace dirty filter.
Low on refrigerant charge causing inefficient operation.
Check for defective compressor. If discharge is too low and suction pressure is too high,
compressor is not pumping properly. Replace compressor and liquid line drier.
Defective reversing valve creating bypass of refrigerant from discharge to suction side of
compressor. Replace reversing valve and liquid line drier.
Compare unit operating pressures to the pressure / temperature chart for the unit.
Check TXV for possible restriction or defect. If replacement is necessary, replace liquid line
drier as well.
The refrigerant system may be contaminated with moisture or noncondensables. Reclaim
refrigerant, evacuate and recharge with factory recommended charge. Note: a liquid line
drier may require replacement.
TROUBLE SHOOTING