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High / Low Refrigerant Pressure Switches
•The high-pressure switch senses the refrigerant pressure in the sealed refrigeration system
and shuts the heat pump down in the event unsafe operating pressures are reached. The heat
pump will automatically reset after the system pressure drops back to normal operating
pressures. When this switch is tripped, digital displays will read “EE1”
•The low-pressure switch senses the refrigerant pressure in the sealed refrigeration system
to protect against certain conditions that could be detrimental to compressor life. The switch
shuts the unit down in the event of loss of refrigerant or not enough refrigerants. The switch
automatically resets when the pressure rises to normal operating pressures. The display will
show “EE2” if this switch is tripped.
Low Ambient Temperature
If the air outside the heat pump is not warm enough to produce heat, the system will shut
down. The actual point at which your unit will shut down due to low temperature varies
depending on current weather conditions, the amount of sunlight reaching the heat pump.
The shutdown can occur anywhere within a wide range of temperatures, usually below 0
degrees. A shutdown occurs because low temperatures will activate the systems
low-pressure safeguard switch (digital controller will display a code “PP7”.) The unit will
start up again when the temperature has raised enough to reset this switch.
Time Delay
All models use a 3-minute time delay to prevent repeated tripping of the compressor thermal
overload, which is caused by attempting startup before system pressures are equalized. Any
interruptions, outside of power loss, will result in a 3-minute time delay.
