McQuay M4AC040A Installation And Maintenance Manual Download Page 8

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shows the code of the USER parameter that can be modified. Pressing the

and

buttons

allows to scroll all USER parameters. Press SEL again to display the required USER parameters and
modify its value (with the

and

buttons). Press PRG to store the modified parameters and exit

the procedure, while the SEL button allows to return to the USER parameters menu.

Setting and Displaying FACTORY-SET Parameters

Factory-set parameters are configuration parameters and so they are protected by a password (177) to
prevent any unauthorized access to the data. Press PRG and SEL simultaneously for more than 5
seconds to enter the factory-set parameters (unit configuration parameters) menu. This section is
protected by a code (password), which is different from the USER one, to prevent any unauthorized
access to the data. Setting the password: “00” flashes on the display. Pressing the

and

buttons

will allow you to stop the blinking effect for a few seconds and select the password value (177); then
press SEL to directly enter the factory-set parameters section. On setting the password, the display will
automatically flash after a few seconds if no buttons are pressed. FACTORY set parameters selection:
the display shows the code of the factory-set parameter that can be modified. Pressing

and

allows to scroll all FACTORY-set parameters. Press SEL again to display the required FACTORY
parameter and modify its value (with the

and

buttons). Press PRG to store the modified

parameters and exit the procedure, while the SEL button allows to return to the FACTORY parameters
menu.

Muting the Buzzer

Press the MUTE button to silence the buzzer.

Resetting ALARMS

Press

and

for more than 5 seconds to reset any alarm condition (manual reset). The

relative LED light will turn off and the alarm relay will disenergize.

Forcing a DEFROSTING Cycle

To force a defrosting cycle press the SEL and buttons

for more than 5 seconds (if the

temperature/pressure values of the outdoor exchanger are lower than the values set for the end of
defrosting

Enabling/Disabling of COOLING Operating Mode

The cooling operating mode can be enabled/disabled by pressing the button

for more than 5

seconds. It is not possible to directly pass from the heating to the cooling operating mode if before the
heating mode is not unprimed: if the unit is actually operating in the heating mode, pressing the button
will not swap the mode.

Enabling/Disabling of HEATING Operating Mode

The heating operating mode can be enabled/disabled by pressing the button

for more than 5

seconds. It is not possible to directly pass from the Cooling mode to the Heating operating mode: It is
necessary to inhibit the Cooling mode.

Stand-by

To turn off the unit, deactivate the current operating mode (Cooling or Heating). When the µchiller is
turned off, it keeps the 4-way valves in the previous position for a period equal to pump OFF delay
after the compressor is OFF.

Reset Timers

When the display shows the operating hours of the compressor or of the pump, you can reset the timer
by pressing the

and

buttons. In this case the unit will not prompt the relative compressors

maintenance message.

Copying the KEY in the Unit’s eeprom

Press PRG and

at µchiller start-up to copy the removable hardware key into the eeprom of the

unit. When the procedure is over, the display will show ‘CE’ to confirm the operation.

Copying the Unit’s eeprom in the Key

Press PRG and

at µchiller start-up to copy the unit’s eeprom into the removable hardware key.