Check that the box includes the following parts in addition to this installation manual:
WARNING
CAUTION
WARNING
The thermostat should be configured for use with a conventional system (not heat pump).
Thermostat Interface terminals | |
Terminal | Purpose |
TC | C: common (in) |
C | C: common (out) |
TR | R: 24 VAC (in) |
R | R: 24 VAC (out) |
G3 | High fan speed |
G2 | Medium fan speed |
G1 | Low fan speed |
Y2 | Stage 2 cooling |
Y1 | Stage 1 cooling |
W2 | Stage 2 heating |
W1 | Stage 1 heating |
G | Fan |
Upon receiving the initial request from the thermostat for the heating/cooling mode, the Thermostat Interface switches to the heating/cooling mode.
For indoor units that support Mode 25 and Mode 27 initial settings, the G signal at the time of entering the heating/cooling mode determines the fan state during thermal off. If the G signal was on, the thermal off fan is on. If the G signal was off, SW1-2 and SW 2-5 settings determine the thermal off-fan speed.
Once there is no longer a request from the thermostat for heating or cooling, the Thermostat Interface switches the indoor unit to either off or fan mode depending upon whether the G signal is off or on. If SW1-1 has enabled delay time, the unit remains in heating or cooling mode for 2 hours before switching to off or fan mode.
Example 1: Two-stage cooling and heating
Example 2: Single-stage cooling and heating
Example 3: Single-stage cooling and heating with dedicated fan speed relays
Example 4: Single-stage cooling with an alternate primary heating source
Note: For this configuration, it is recommended to set SW2-6 to the ON position.
Follow the wiring from Example 2 with the following adjustments:
Functions of DIP switch
Zero delay timer
SW1-1 | Delay timer |
OFF | Stay in heating or cooling mode for 2 hours once W1 or Y1 is no longer active, which provides more efficient operation but does not respond to fan request changes (G) during the 2 hours. This setting allows more time for defrost timers in the outdoor unit to run (default). |
ON | Once heat or cool request W1 or Y1 is no longer active, the system turns off or goes into fan mode immediately depending on the G signal. This is less efficient operation but responds more quickly to fan request changes. This setting operates most like the previous Thermostat Interface with zero hold time after achieving set point. |
SW1-2 | Mode 27 / Fan speed |
OFF | 2 (default) / Off |
ON | 3 / Extra low |
SW1-3 | SW1-4 | Result |
OFF | OFF | Custom Auto (default) |
ON | OFF | Medium |
OFF | ON | High |
ON | ON | Auto |
Note: Custom Auto (default) provides higher fan speeds for more comfortable fan speed operation vs. the more efficient Auto.
Two-stage thermostat operation
SW2-6: Adjusts indoor unit operation during stage 1 heating (W1) and stage 1 cooling (Y1) according to the following table:
SW2-6 | Operation during stage 1 |
OFF | The capacity is adjusted so that the room temperature is adjusted (heated or cooled) at a fixed rate (default). |
ON | Full capacity |
Note: When either Y2 or W2 is left unconnected, it is recommended to set SW2-6 to the ON position. When both Y2 and W2 are connected, it is recommended to set SW2-6 to the OFF position.
Static pressure settings
SW2-1, SW2-2, SW2-3: Adjust the static pressure function settings of the indoor unit according to the following table:
DIP switch position on PAC-US445CN-1 | Indoor unit settings | |||||
SW2-1 | SW2-2 | SW2-3 | Mode 8 | Mode 10 | Mode 23 | Mode 11 |
OFF | OFF | OFF | Not set | Not set | Not set | Not set |
OFF | OFF | ON | Not set | Not set | Not set | Not set |
OFF | ON | OFF | 2 | 1 | Set by SW2-4 | 2 |
OFF | ON | ON | 2 | 2 | Set by SW2-4 | 2 |
ON | OFF | OFF | 1 | 1 | Set by SW2-4 | 2 |
ON | OFF | ON | 1 | 2 | Set by SW2-4 | 2 |
ON | ON | OFF | 3 | 1 | Set by SW2-4 | 2 |
ON | ON | ON | 3 | 2 | Set by SW2-4 | 2 |
Refer to the appropriate indoor unit installation manual for Mode 8 and Mode 10 function setting definitions.
SW2-4: Adjusts Mode 23 function settings according to the following table:
SW2-4 | Mode 23 |
OFF | 1 (default) |
ON | 2 |
Refer to the appropriate indoor unit installation manual for Mode 23 function setting definitions. For Mode 23 function settings for the PAA unit, refer to the “Usage with PAA unit” section in this manual.
Fan speed during heating mode, thermal off
SW2-5: Adjusts Mode 25 initial setting according to the following table.This setting depends upon whether it is more important to stop the fan or to keep the air moving when not heating.
SW2-5 | Mode 25 / Fan speed |
OFF | 2 (default) / Off |
ON | 1 / Extra low |
Thermostat Interface non-changeable function settings
In addition, the thermostat interface also affects the following function settings of the connected indoor unit.
Mode | When using the thermostat interface |
Mode 1 (auto recovery after power failure) | Always enabled |
Mode 2 (room temperature detection location) | Unused (room temperature detected by the connected thermostat) |
Mode 24 (heat offset for height) | Unused |
Additional function settings not addressed by the Thermostat Interface may be configured by temporarily connecting an MA remote controller. Indoor unit Mode settings only work for M-Series indoor units that begin with an “S” and P-Series units.
Make sure power supply to the indoor unit is off. We also recommend configuring the DIP switch settings (see “Device configuration” section) before installing the Thermostat Interface.
Grouping
The connection of more than one PAC-US445CN-1 to a single set of thermostat dry contacts is not supported.
Temperature sensing
The PAC-US445CN-1 relies upon both the 24 VAC thermostat and the indoor unit’s thermistors in order to monitor room temperature. The thermostat’s temperature sensing is used to set the room temperature. The indoor unit thermistor is used when calculating cooling and heating rates of change.
Operate the third-party thermostat per the manufacturer’s instructions. During normal operation, the connection of Mitsubishi Electric remote controllers (e.g. MA/ME) is not supported as they will interfere with the correct operation of the PAC-US445CN-1.
Notes:
The PAC-US445CN-1 Thermostat Interface 2 must be installed in the PAA unit control box if a third-party 24 VAC thermostat is used to control the PAA unit. Previous Thermostat Interface PAC-US444CN-1 is not compatible with the PAA unit.
How to install Thermostat Interface in PAA unit control box
Make sure power supply is off.
Cable assembly connections to the Thermostat Interface 2 | |
Wire color | Signal |
Green | G: fan |
White | W1: first stage of heating |
Brown | W2: second stage of heating |
Yellow | Y1: first stage of cooling |
Blue | Y2: second stage of cooling |
Light blue | C: 24 VAC return |
Red | R: 24 VAC hot |
Thermostat power supply
The thermostat may receive power from the furnace transformer or may have a separate power supply. An example of when it might have it’s own power supply is when using a damper control system as dampers typically require more power than the furnace transformer can supply.
SW01-1: Determines whether to allow the thermostat to provide its own power or allow the furnace to supply power to the thermostat in Emergency and Normal operation modes according to the following table:
SW01-1 | Result |
OFF | Electronically disconnects the R line from the furnace to the auxiliary control equipment and allows the auxiliary equipment to provide its own power. |
ON | Electronically routes the R line from the furnace through the PAA unit control box to the thermostat terminals if connections within the PAA unit control box provide operating power to the thermostat in Emergency and Normal operation modes (default). |
SW01-4: Determines Emergency and Test mode operations according to the following table:
SW01-4 | Result |
OFF | Thermostat (or non-adjustable thermostat, if used) controls the heat and fan signals applied to the furnace during Emergency operation modes (default). |
ON | Test mode operation |
For information about the non-adjustable thermostat and Test mode operation, refer to the PAA unit installation manual.
Thermostat Interface DIP switch settings for PAA unit only
SW2-4: Adjusts PAA unit Mode 23 function settings according to the following table.
Note: This DIP switch is on the Thermostat Interface, not the relay board of the PAA unit.
If the furnace does not support two fan speeds via Y1 and Y2, set Mode 23 to 1 for G and Y.
If the furnace supports two fan speeds via Y1 and Y2, to allow that to be used when cooling or heating using the heat pump, set Mode 23 to 2. For Mode 23 setting 2, the recommended DIP switch SW1-3/4 setting is Auto to vary fan speed, not Custom Auto.
SW2-4 | Mode 23 |
OFF | 1 (default) |
ON | 2 |
Refer to the PAA unit Installation Manual for connections to the furnace based upon the setting of Mode 23.
After changing the Mode 23 setting, you need to power cycle the system for the change to reliably take effect
Download Manual
MITSUBISHI ELECTRIC PAC-US445CN-1 Thermostat Installation Manual
MITSUBISHI ELECTRIC PAC-US445CN-1 Thermostat Installation Manual
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