Trane SCXG-SVX01B-EN manual Maintenance troubleshooting, System Checks, Live Electrical Components

Maintenance troubleshooting

System Checks

￿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.

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 bel 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 compres- sor 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 is:

(221+230+227) = 226 volts 3

Therefore, the percentage of voltage imbalance is:

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.

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
Microbial growth (mold)	Standing water in drain pan	See “Standing water in drain pan” above
	Moisture problems	See “Wet interior insulation” above

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