FAXA-SVX01B-EN
81
Maintenance
maintenance
procedures
Table M-MP-1. Common unit problems and solutions
problem
possible cause
remedy
drain pan is overflowing
plugged drain line
clean drain line
unit not level
level unit
standing water in drain pan
unit not level
level unit
plugged drain line
clean drain line
wet interior insulation
coil face velocity too high
reduce fan speed
improper trap design
design trap per unit installation
instructions
drain pan leaks/overflowing
repair Leaks
condensation on surfaces
insulate surfaces
excess dirt in unit
missing filters
replace filters
filter bypass
reduce filter bypass
System Checks
Before proceeding with technical trouble
charts or controls checkout, complete the
follow system analysis:
1. Measure actual supply voltage at the
compressor and at motor terminals
with the unit running. Voltage must be
within the range listed on the motor
nameplate. Phase imbalance must be
less than 2.0% between phases.
2. Check all wiring and connections to be
sure that they are intact, secure and
properly routed. The as wired system
diagrams are provided in the unit
control panel.
3. Check that all fuses are installed and
properly sized.
4. Inspect air filters and coils to ensure
airflow to the unit is not restricted.
5. Check the zone thermostat settings, if
applicable.
6. Ensure the fan is rotating in the proper
direction. If phasing is wrong at the
main power terminal block, the fan and
compressors will not run.
7. Inspect ductwork and duct connections
for tightness.
8. Verify all applicable settings on the
human interface (HI).
WARNING
Live electrical components!
During installation, testing, servicing,
and troubleshooting this equipment, it
may be necessary to work with live
electrical components. Have a
qualified licensed electrician or other
properly trained individual perform
these tasks. Failure to follow all
electrical safety precautions when
exposed to live electrical components
can cause death or serious injury.
Operating Procedures
Install pressure gauges on the discharge
and suction line access valves. When the
unit has stabilized (after operating
approximately 15 minutes at full load),
record suction and discharge pressures.
System malfunctions such as low airflow,
line restrictions, incorrect refrigerant
charge, malfunctioning of expansion
valves, damaged compressors, and so
on— will result in pressure variations
which are outside the normal range.
Note: If phasing at the main incoming
power terminal is incorrect, switch two
of the three incoming power leads. If a
compressor has been replaced and the
phase is changed at the compressor, it
will run backwards and discharge
pressure will be very low. To resolve
incorrect compressor wire phasing,
change phasing at the compressor.
It is important that pressures be mea-
sured under stable and constant condi-
tions in order for the readings to be
useful.
Voltage Imbalance
Voltage imbalance on three-phase
systems can cause motor overheating
and premature failure. Maximum
allowable imbalance is 2.0% and the
readings used to determine it must be
measured at the compressor terminals.
Voltage imbalance is defined as 100
times the sum of the division of the three
voltages from the average voltage. If, for
example, the three measured voltages
are 221, 230, 227, the average would be:
(221+230+227) = 226 volts
3
The percentage of voltage imbalance is
then:
100*(226-221) = 2.2%
226
In this example, 2.2% imbalance of more
than 2.0% exists, be sure to check the
voltage at the unit disconnect and
terminal block switch. If an imbalance at
the unit disconnect switch does not
exceed 2.0%, the imbalance is caused by
faulty wiring within the unit. Be sure to
conduct a thorough inspection of the unit
electrical wiring connections to locate the
fault, and make any repairs necessary.