System Operation - Maytag Amana PTH153K50 Series Service And Troubleshooting

SYSTEM OPERATION

NOTE:
The heat pump and electric heat DO NOT operate together,
it is either in electric heat or heat pump mode.
CONTROL BOARD CHARACTERISTICS
• Automatic 3-minute Compressor Lockout - After the
compressor cycles off, it will not restart for three
minutes. This feature is enabled in standard or remote
thermostat control.
• Compressor lock-in feature - Whenever the
compressor is switched from off to on because
the room temperature has risen above or fallen
below the specified limit it will remain on for at least
four minutes. However, if the thermostat point is
changed during the four minutes this lock in feature is
overridden.
• Automatic 2nd Stage Electric Heat (Heat Pump
Models) - If the room temperature falls to 4°F below
the set point temperature, the reverse cycle heat
pump is shut off and the strip heat is turned on.
• Automatic Freeze Protection - Whenever power is
supplied to the unit and the master switch is in the ON
position, automatic freeze protection is active. If the
thermistor senses temperature below 40°F+/-5°F, the
fan motor and electric strip heat (or hydronic heat, if
applicable) are switched on. The heater and fan will
remain on until the Thermistor senses a temperature
of 43°F.
• Remote Thermostats - Always use an approved
thermostat supplied by the manufacturer. A wall
thermostat that has not been approved by the
manufacturer may not work correctly with this unit.
• Remote Functions - All functions are controlled by a
wall mounted thermostat.
• Remote Fan - When GL terminal is connected to R
terminal the remote fan speed is switched to low. GH
terminal connected to the R terminal fan speed is
switched to high.
• Fuse Protection - The fuse protection has been
maximized on the 24 volt circuit so accidental
groundings of the external terminals will not result
in a burned out board. The unit may be operated
in standard mode if the fuse is blown. There will be
an auxiliary fuse supplied with the board. It will be
attached to the main fuse by a plastic clip. The fuse is
a 500 ma fuse. When replacing the fuse always use
the correct fuse part #M0804205.
• Random Delay - When the master switch is turned on
or power is reapplied to the control, all functionality
will be locked out for a random period between two
and four minutes, if Y or W inputs are active in remote
or the mode switch is set to HI/LO heat or cool. The
delay can be avoided if the front desk terminals are
closed for more than two seconds, or the mode switch
is in the off or fan only position.
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• Indoor Ambient Thermistor - The Indoor Ambient
Thermistor senses actual room temperature.
• Indoor/Outdoor Coil Thermistors - In the cooling
mode, if the compressor is engaged continuously for
20 minutes and the Indoor Coil Thermistor is below 30
degrees the compressor is disengaged until the ICT
rises above 45 degrees. The Outdoor Coil Thermistor
senses coil temperature which correlates to outdoor
air temperature. Heat pump operation can operate
as low as 24°F outdoor temperature depending upon
humidity conditions and / or the balance point of the
system. After defrost is initiated, the compressor
remains off for at least thirty minutes and resumes
operation when the outdoor coil temperature reaches
33°F. Electric resistance heat will maintain the
ambient room temperature anytime the temperature
falls 4°F below the room set point temperature.
• Load Shedding - The IN & COM terminals are used
for load shedding. A switch can be added to close the
circuit to lock out the compressor and electric heat
when the power company or energy management
system is trying to reduce its load for a specified time.
• Sample Before Start - The SBS routine is used in
the cooling mode. This routine runs the unit fan on
low speed for up to 120 seconds. The sample fan is
aborted if compressor demand is detected. To avoid
unnecessary sampling the period between samples
will be based on specific room conditions. The default
sample before start period after a power up is 5
minutes. The period is corrected every time a sample
run is completed without a compressor demand.
The minimum sample period is 5 minutes and the
maximum period is 15 minutes.
• Front Desk Control - The front desk control terminals
are IN and COM. These terminals will provide a
connection for a user supplied switch that will allow
the operation of the unit to be remotely defeated.
• Transfer Fan - A transfer fan may be used if a user
supplied relay is connected to IN and COM. Make
sure the relay is a manufactured approved relay. The
relay will be energized whenever the blower/fan relay
is energized.
• Emergency Hydronic Heat - A switch can be added
to the IN & COM terminals to close the circuit to
enable the fan, enable the heater relay and lockout
the compressor to continue minimum operations with
auxiliary power, if the main power goes out.
OPERATING CONTROLS
USERS CONTROLS
The unit will be controlled by a Wired Wall Thermostat or
the Amana Wireless Thermostat.