12
Subject to change without notice.
Thermostat Bypass
The unit also has a Thermostat Bypass Switch
which is used to manually force cooling or heating
to be energized based on the mode selected by
the Selector Switch. Thermostat bypass over-
rides the unit’s on-board thermostat and the
Remote Thermostat. Both of the thermostats
become non-functional in the bypass mode.
To operate in Bypass Mode, set the Selector
Switch to the desired mode of operation (COOL
or HEAT). Set the Thermostat Bypass Switch to
the BYPASS position. At this point either COOL or
HEAT will operate continuously without shutting
down.
UNIT SAFETY DEVICES
Evaporator Motor Overload
The evaporator and condenser motors are
protected by thermal overloads. The evaporator
blower motor protection is internal and
automatically resets once the temperature
inside the windings of the motor falls below the
temperature trip point.
Condenser Motor Overload
The condenser blower motor is external and
protected manually with an overload block. This
overload block is tied directly to the condenser
motor contactor (CCM). This is a manual reset
overload. If the condenser motor for any reason
should cut out on overload, disconnect power
using the unit’s circuit breaker then open the main
control box. Press the reset button on the CCM
overload block. Refer to the troubleshooting guide
section for information on troubleshooting.
High Pressure Switch
The compressor system has a manual reset High
Pressure Switch. If the unit is not providing cooling
as evidenced by the Return Air Temperature “AIR
IN” being approximately equal to the Supply Air
Temperature “AIR OUT”, the compressor system
may have tripped on high refrigerant pressure.
Disconnect power using the unit’s circuit breaker.
Remove the Access Panel to the Compressor
Compartment and locate the Manual Reset High
Pressure Switch. Press the button downward to
verify if the switch tripped. If the button clicks the
unit tripped on high pressure. Replace the access
panel then reapply power using the unit’s circuit
breaker. Set the unit to Cool Mode. Refer to the
Troubleshooting section for causes and corrective
actions. It may require a service technician to
check system pressures if the switch trips more
than 1-2 times.
Low Pressure Switch
The compressor system has an automatic reset
low pressure safety switch. If the unit trips on
low pressure, the compressor will shut down but
automatically restart once the switch resets. The
low pressure switch shuts down the compressor
system if the refrigerant pressure falls below 70
psig and automatically restarts the compressor
once the pressure rises above 100 psig.
Compressor Internal Overload
Each compressor has an internal motor
overload switch. This switch opens to protect the
compressor motor when the temperature within
the windings of the compressor motor exceeds
the high temperature trip point. When this switch
opens, the compressor motor will continue to
operate but the compressor pumping mechanism
“scroll” will become disconnected. To reset this
condition, the power must be disconnected from
the compressor contactor. Set the unit back to the
FAN position and allow the unit to operate in the
FAN position for approximately 30- 45 minutes.
This should be enough time to cool the windings of
the compressor motor which will allow the switch
to reset (re-engaging the scroll). Set the Selector
Switch back to COOL mode and the compressor
should re-start. If this compressor goes out on
internal overload condition, check the voltage.
Since the compressor motor windings are cooled
by the refrigerant gas as it enters the compressor,
the unit may also be low on refrigerant.
