182-361 Nominal Capacity Compressor Motor Protection Module Diagnosis - Trane Start to Finish R-410A Installation Manual

Troubleshooting
– Liquid line solenoid valve does not open (if so
equipped).
– Dirty evaporators, either air-to-air or water-to-air.
– Restricted airflow.
– Insufficient evaporator water flow.
– System undercharged with refrigerant. Check
system superheat and subcooling.
Compressor short cycling
• Check the unit Installation, Operation, and
Maintenance manual for possible diagnostics codes
and corrective action.
• Also check for:
– Defective unit controls—maximum 12 starts per
hour.
– Compressors cycling on safety controls.
– Unit oversized.
– Building load is light—this is likely to occur prior to
building occupancy.
Motor protector module resets
• Type: Manual
Fault modes:
– Phase sequence
– Phase loss
– Multiple motor temperature overload cycles.
Reset—Remove power from module for five seconds.
• Type: Auto with five-minute delay (sensors exceed
4500 ohms)
Fault modes:
– Over current
– Running phase loss
– Motor over temperature (manual reset required
after 2-5 auto reset cycles)
Reset—Auto-reset occurs when motor temperature
sensors resistance drops below 2750 ohms. Although
module will reset automatically the compressor(s)
may not because the protection module may be wired
in a safety lockout circuit.
Incorrect phase sequence
Incorrect phase sequence protection—compressor will
run approximately five seconds and trip off, pending the
motor protection module is correctly wired into the
system safety circuit. If the motor is believed to be
incorrectly phased; change two of the three wires.
PTC Overheat (motor over temperature/over
current)
• Compressor motor drawing too much current.
32
• Defective compressor; look for dark oil in the
sightglass.
• Low voltage (voltage outside the ±10% range from
nominal voltage); voltage utilization range is printed
on compressor nameplate.
• Unbalanced voltage—must not exceed 2% imbalance.
• Motor PTC thermistor resistance above 4500 ohms will
cause the motor protector to open. The motor
protector will reset at resistance below 2750 ohms. A
five-minute time delay is active after cool down until
the maximum number of auto reset cycles has been
reached. The module will then be locked out until it is
manually reset.
NOTICE
Excessive Voltage on PTC Sensors!
Failure to follow these instructions could cause
thermistor failure, resulting in a compressor
replacement. Do not measure the motor PTC sensors
with a device rated at more than 3 Vdc.
• When measuring the PTC sensors, do not use a meter
with greater than 3 Volt.
• 360–361 nominal capacity compressor internal relief
valve has opened.
• Phase loss.
• Defective contactor.
• Loose or poor electrical connections at the compressor
or contactor.
182–361 Nominal Capacity Compressor
Motor Protection Module Diagnosis
WARNING
Hazardous Service Procedures!
Failure to follow all precautions in this manual and on
the tags, stickers, and labels could result in death or
serious injury.
Technicians, in order to protect themselves from
potential electrical, mechanical, and chemical hazards,
MUST follow precautions in this manual and on the
tags, stickers, and labels, as well as the following
instructions: Unless specified otherwise, disconnect all
electrical power including remote disconnect and
discharge all energy storing devices such as capacitors
before servicing. Follow proper lockout/tagout
procedures to ensure the power can not be
inadvertently energized. When necessary to work with
live electrical components, have a qualified licensed
electrician or other individual who has been trained in
handling live electrical components perform these
tasks.
If M1-M2 contacts are open, proceed as follows:
1. Check motor protection module for the correct input
voltage on terminals L and N. Voltage applied to
PART-SVN234B-EN