Installation and Maintenance Manual

104 SCXG-SVX01H-EN
Diagnostics
Troubleshooting
System Checks
Before proceeding with technical trouble charts or controls
checkout, complete the following system analysis:
1. Measure actual supply voltage at the compressor and
an 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%.
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 be sure that airflow to the
unit is not restricted.
5. Check the zone thermostat settings.
6. Ensure that 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 correctly.
7. Inspect ductwork and duct connections for tightness.
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, etc. 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 measured under stable
and constant conditions 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 is:
Therefore, the percentage of voltage imbalance is:
100*(226-221)/226 = 2.2%
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.
Diagnostics
Refer to the IntelliPak Self-Contained Programming Guide,
PKG-SVP01B-EN, for specific unit programming and
troubleshooting information. In particular, reference the
“Service Mode Menu” and “Diagnostic Menu”sections in
the programming guide. Refer to the following text for
general diagnostic and troubleshooting procedures.
Common diagnostics and troubleshooting procedures
follow below.
WARNING
Live Electrical Components!
During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical
safety precautions when exposed to live electrical
components could result in death or serious injury.
Table 55. Common unit problems and solutions
Problem Possible Cause Remedy
Drain pan is
overflowing
Plugged drain line
Unit not level
Clean drain line
Level unit
Standing water in
drain pan
Unit not level
Plugged drain line
Level Unit
Clean drain line
Wet interior insulation
Coil face velocity too
high
Improper trap design
Drain pan leaks/
overflowing
Condensation on
surfaces
Reduce fan speed
Design trap per unit
installation
instructions
Repair Leaks
Insulate surfaces
Excess dirt in unit
Missing filters
Filter bypass
Replace filters
Reduce filter bypass
Microbial growth
(mold)
Standing water in
drain pan
See "Standing water in
drain pan" above
Moisture problems
See “Wet interior
insulation” above
221 230 227++
3
--------------------------------------------------- - 226volts=