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DESCRIPTION OF STANDARD
EQUIPMENT
High Pressure Switch
Provides refrigerant circuit high pressure protection.
Includes lockout circuit that is resettable from room
thermostat.
Compressor Control Module
Provides short cycle protection for the compressor
which extends compressor life. High and low pressure
switch monitoring and alarm functions.
Service Lights
One service light indicates when service is required.
• Check System – detects high or low pressure
switch operation for compressor protection.
OPTIONAL CFM (QA361, QA421, QA481
AND QA601 ONLY)
These units are shipped from the factory set to operate at
the optional CFM level shown in Table 7. This provides
lower operating sound levels for non-ducted, free
discharge applications. This CFM level will reduce the
system capacity performance by approximately 2% at
the same energy efficiency.
Rated CFM is required for ducted applications for
maximum performance rating. To obtain full CFM on
these models, connect jumper wire as follows:
1. Disconnect all power to the unit. Failure to do so
may result in damage to the motor.
2. Open return air service panel
3. Open inner control panel cover
4. Locate low voltage terminal strip. There is a pink
jumper wire with both ends attached to terminal
marked "G2". Move one end of this jumper to
terminal "Y".
5. Reverse steps to reassemble.
IMPORTANT INSTALLER NOTE
For improved start-up performance, wash the indoor coil
with a dishwasher detergent.
This unit is equipped with a variable speed ECM motor.
The motor is designed to maintain rated airflow up to
the maximum static allowed. It is important that the
blower motor plugs are not plugged in or unplugged
while the power is on. Failure to remove power prior
to unplugging or plugging in the motor could result in
motor failure.
Manual 2100-437E
Page
22 of 31
CAUTION
Do not plug in or unplug blower motor
connectors while the power is on.
Failure to do so may result in motor failure.
PHASE MONITOR
All units with three phase scroll compressors are
equipped with a 3 phase line monitor to prevent
compressor damage due to phase reversal.
The phase monitor in this unit is equipped with two
LEDs. If the Y signal is present at the phase monitor
and phases are correct the green LED will light and the
compressor contactor is allowed to energize.
If phases are reversed, the red fault LED will be lit and
compressor operation is inhibited.
If a fault condition occurs, reverse two of the supply
leads to the unit. Do not reverse any of the unit factory
wires as damage may occur.
THREE PHASE SCROLL COMPRESSOR
START UP INFORMATION
Scroll compressors, like several other types of
compressors, will only compress in one rotational
direction. Direction of rotation is not an issue with
single phase compressors since they will always start
and run in the proper direction.
However, three phase compressors will rotate in either
direction depending upon phasing of the power. Since
there is a 50-50 chance of connecting power in such a
way as to cause rotation in the reverse direction,
verification of proper rotation must be made.
Verification of proper rotation direction is made by
observing that suction pressure drops and discharge
pressure rises when the compressor is energized.
Reverse rotation also results in an elevated sound level
over that with correct rotation, as well as, substantially
reduced current draw compared to tabulated values.
Verification of proper rotation must be made at the
time the equipment is put into service. If improper
rotation is corrected at this time there will be no
negative impact on the durability of the compressor.
However, reverse operation for even one hour may
have a negative impact on the bearing due to oil pump
out.
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