TemperZone UC8 User manual

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 1 of 27
UNIT CONTROLLER 8 (UC8)
Operation Manual
Split System models: OSA–RLF
Date: 24 November 2020
Issue: 1
Note: Information in this document applies to UC8 controllers with
software version 6.1.2-55 and installed in models OSA-RLF
To find the UC8 software version:
Turn on mains power to the UC8 controller and observe the seven-segment display.
The display will show the characters “UC8”, followed by the software version, build
number and software identification code (SHA).

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 2 of 27
Contents
1. UC8 circuit board input and output signals ........................................................... 4
1.1. Mains power ....................................................................................................................... 4
1.2. Low voltage signals ............................................................................................................. 4
1.3. Temperature sensor inputs................................................................................................. 4
1.4. Pressure transducer inputs ................................................................................................. 4
1.5. Inputs HI, ME, LO, CAP and HT............................................................................................ 5
1.6. Remote On/Off input .......................................................................................................... 5
1.7. Variable speed indoor fan control input VF (0-10V)........................................................... 5
1.8. Variable capacity control input VC (0-10V)......................................................................... 5
1.9. Reverse cycle valve output R/V........................................................................................... 5
1.10. Solid state relay output SSR#1 ............................................................................................ 5
1.11. Relay outputs CMC, LOW, MED and HIGH, SSR#2.............................................................. 6
1.12. On-status output AUX......................................................................................................... 6
1.13. Input IN#1............................................................................................................................ 6
1.14. Input IN#2............................................................................................................................ 6
1.15. Modbus RTU serial communication port 1 ......................................................................... 6
1.16. Modbus RTU serial communication port 2 ......................................................................... 6
1.17. Electronic expansion valves ................................................................................................ 6
1.18. Inputs D1, D2 and D3 .......................................................................................................... 6
2. DIP switch settings ................................................................................................ 7
3. Digitally communicating thermostats: SAT-3 and TZT-100 .................................... 8
3.1. Temperzone SAT-3 room thermostat ................................................................................. 8
3.2. Temperzone TZT-100 room thermostat ............................................................................. 8
3.3. Thermostat communication settings.................................................................................. 9
4. Connecting to external devices using Modbus RTU over RS485 ............................ 9
5. Connecting the indoor unit.................................................................................. 10
5.1. Making a reliable connection between the outdoor- and indoor- unit ........................... 10
5.2. Connecting 1 outdoor unit to 1 indoor unit...................................................................... 10
5.3. Connecting 1 outdoor unit to 2 indoor units.................................................................... 11
6. Capacity control .................................................................................................. 11
6.1. 0-10V control..................................................................................................................... 11
6.2. Supply air temperature control ........................................................................................ 11
6.3. Automatic control with SAT-3 or TZT-100 thermostat ..................................................... 12
6.4. Modbus RTU control ......................................................................................................... 12
6.5. Oil recovery (oil flush) cycles ............................................................................................ 13

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 3 of 27
7. Dry mode (de-humidification) ............................................................................. 13
7.1. Dry mode and the SAT-3 thermostat................................................................................ 13
7.2. Dry mode and the TZT-100 thermostat ............................................................................ 14
8. Indoor fan control ............................................................................................... 14
8.1. Indoor fan speed adjustment............................................................................................ 15
8.2. Translation from 0-10V fan control input signal VF to a fan output signal ...................... 16
9. Display messages................................................................................................. 17
10. Special modes ..................................................................................................... 19
10.1. Factory test mode: t.......................................................................................................... 20
10.2. Commissioning mode: c.................................................................................................... 20
10.3. Compressor selection mode: E ......................................................................................... 20
10.4. Supply-air temperature control option: Y......................................................................... 20
10.5. Thermostat auto-on/off options: o................................................................................... 21
11. Troubleshooting.................................................................................................. 22
11.1. Fault codes ........................................................................................................................ 22
11.2. Inverter fault codes........................................................................................................... 24
12. UC8 controller circuit board specifications.......................................................... 25

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 4 of 27
1. UC8 circuit board input and output signals
1.1. Mains power
Terminal
L
Mains live 230V AC
N
Mains neutral
EARTH
Protective earth
NOTE! The EARTH terminal on the UC8 controller board MUST always be
directly connected to the unit earth stud.
1.2. Low voltage signals
HI, ME, LO, CP and HT: Control signal inputs, 24V AC or 12V to 24V DC
DL, SL, AMB, DEI, OC, IC: Inputs for Temperzone standard temperature sensors
HPT, LPT: Inputs for Temperzone standard pressure transducers
IN#1, IN#2, D1, D2, D3, On: Control signal inputs for voltage free relay contacts
VC, VF: Control signal inputs, 0-10V analogue
A1, B1, A2, B2: Communication ports, RS485 Modbus RTU
HIGH, MED, LOW, C3, C4: Relay contact outputs
CMC, R/V: Relay contact outputs
SSR#1, SSR#2: Solid state relay contact outputs
V1 and V2: Control signal outputs, 0-10V analogue
EXV1, EXV2: Outputs for 12V DC uni-polar electronic expansion valves
AUX, FLT, EXV2: Outputs for 12V DC relay coils
Notes: The UC8 controller cannot accept 230V AC signals on any of the low voltage inputs!
Terminals marked “0V” and “SC” are electrically directly connected to the EARTH terminal.
1.3. Temperature sensor inputs
Connector
Function
Sensor wire colour
DL
Compressor discharge gas temperature sensor
Grey
SL
Compressor suction gas temperature sensor
White
AMB
Outdoor ambient temperature sensor
Black
DEI
Outdoor coil de-icing sensor
Blue
1.4. Pressure transducer inputs
Connector
Function
Pressure range
Output voltage
HPT
Compressor discharge gas pressure (HP)
0 to 4500kPa
0.5 to 4.5V
LPT
Compressor suction gas pressure (LP)
0 to 3450kPa
0.5 to 4.5V

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 5 of 27
1.5. Inputs HI, ME, LO, CAP and HT
These inputs are electrically isolated from all other circuits. The inputs can accept 24V AC or 12V DC
signals. A thermostat or other controller can be connected as follows:
CP Compressor on/off
HT Cooling / heating
HI –ME –LO Indoor fan speed high / medium / low / off
C1 Common for inputs HI, ME and LO
C2 Common for inputs CP and HT
1.6. Remote On/Off input
A remote on/off signal can be connected to the “On” and “0V” terminals (input for a voltage-free
switch or relay contact). To turn the unit on the remote on/off input must be closed-circuit. When the
unit is off by the remote on/off signal the display will show a slowly flashing –symbol. The remote
on/off input cannot override the compressor minimum run-time of 90 seconds.
If no remote On/Off function is needed then the terminals must be connected (shorted).
When the remote on/off input is used in combination with a SAT-3 or TZT-100 thermostat then refer
to chapter 0: Thermostat auto–on/off options.
1.7. Variable speed indoor fan control input VF (0-10V)
Analogue input VF (0-10V) provides an optional input for control of the indoor fan speed.
Notes:
•0-10V input VF is referenced to unit earth, it is not electrically isolated.
•Terminal 0V is the reference (return) connection.
For more information about the indoor fan refer to chapter 8.
1.8. Variable capacity control input VC (0-10V)
New OSA models are equipped with a variable speed compressor (inverter) and thus can provide
variable capacity (duty). If the unit is controlled using the 24V AC / 12V DC inputs then capacity can be
controlled by applying a 0-10V analogue signal to input VC.
Notes:
•0-10V input VC is referenced to unit earth, it is not electrically isolated.
•Terminal “0V” is the reference (return) connection.
•The compressor does not switch off when the voltage on input VC is at 0V. Switching the
compressor on and off is under the control of input CP.
1.9. Reverse cycle valve output R/V
Terminals R/V control the reverse cycle valve. The refrigeration circuit is designed with reverse cycle
valve OFF for cooling mode, ON for heating mode.
1.10. Solid state relay output SSR#1
Output SSR#1 is for control of a compressor crank case heater.

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 6 of 27
1.11. Relay outputs CMC, LOW, MED and HIGH, SSR#2
Reserved.
1.12. On-status output AUX
Output AUX operates the unit status relay SRB. The SRB relay contacts provide an “On-status” signal.
The output is active when one or more of the following conditions apply:
•The compressor is on.
•The indoor fan is on.
•The compressor and indoor fan are currently off but the thermostat is on, e.g. the unit is off
in deadband, or the compressor may be held off by an internal safety timer, or by a
protection function.
1.13. Input IN#1
Reserved, leave open circuit.
1.14. Input IN#2
Input for an overload switch signal. If no overload signal is used the terminals must be shorted.
1.15. Modbus RTU serial communication port 1
Terminals A1 and B1 provide a serial communications port for a building management system (BMS)
or other type of monitoring and/or controlling device. The communications protocol is Modbus RTU
and the signals follow the RS485 standard. On this port the UC8 always acts as a Modbus slave device.
The RS485 signal reference is terminal 0V, which is directly connected to unit earth.
1.16. Modbus RTU serial communication port 2
Terminals A2 and B2 provide a serial communications port for a room thermostat and for the
compressor driver in a unit with inverter compressor. The communications protocol is Modbus RTU
and the signals follow the RS485 standard. On this port the UC8 always acts as a Modbus master
device. Refer to chapter 4.
The RS485 signal reference is terminal 0V, which is directly connected to unit earth.
Terminals “0V” (-) and “12” (+) provide 12V DC power that can be used to power the room
thermostat.
1.17. Electronic expansion valves
The UC8 controls an electronic expansion valve via output EXV1. Output EXV2 is normally not used
but can be used to control a second EEV. The signals on output EXV2 are a duplicate of the signals on
output EXV1.
1.18. Inputs D1, D2 and D3
Reserved, leave open circuit (not connected). Terminal SC is internally directly connected to terminals
labelled ‘0V’ and the EARTH terminal.

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 7 of 27
2. DIP switch settings
Switch
Function
1
OFF
ON
Indoor fan behaviour
Indoor fan speed may vary from the thermostat request.
Indoor fan speed follows the thermostat request.
Note: Thermostat fan settings and protection functions can override the selections
above.
2
OFF
Reserved
Do not select any other setting.
3
OFF
4
ON
Outdoor fan type
Outdoor fan 0-10V control signal on output V1.
5
OFF
6
ON
Reserved
Do not select any other setting.
7
ON
8
OFF
Expansion valve arrangement
Single- or parallel- EEV.
9
OFF
ON
OFF
ON
10
OFF
OFF
ON
ON
Electronic expansion valve type
How to recognise the valve type
Dunan DPF series
Zhe Jiang Sanhua DPF series
Carel E2V series
Reserved, do not select
removable black coil
non-removable metal coil
removable red coil
-
11
OFF
12
OFF
Master / slave selection
Stand-alone unit / master unit.
13
OFF
14
OFF
15
OFF
16
OFF
Models OSA and OPA.

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 8 of 27
3. Digitally communicating thermostats: SAT-3 and TZT-100
The unit can connect to one SAT-3 or to one TZT-100 room thermostat.
It is strongly recommended to use a shielded cable with twisted pair wires. Signals from UC8 terminals
A2 and B2 must form one twisted wire pair. The cable shield should connect to terminal “0V” at the
UC8.
12V DC power is available on terminals “0V” (-) and “12” (+) and can be used to power the
thermostat. If the cable length between the UC8 and thermostat is greater than about 20m and
communications do not work or are intermittent then place UC8 jumper “J2” on the centre and left
pins, otherwise place jumper “J2” on the centre and right pins.
It is recommended to keep the thermostat cable separate from other cables as much as is practical.
When the UC8 and room thermostat are communicating a small
“satellite dish antenna” symbol is visible on the thermostat display:
3.1. Temperzone SAT-3 room thermostat
A typical connection to a SAT-3 room thermostat:
3.2. Temperzone TZT-100 room thermostat
A typical connection to a TZT-100 room thermostat:

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 9 of 27
A TZT-100 thermostat can also be powered by an isolated 24V AC power source:
For all installations DIP switch 4inside the TZT-100 must be ON: Reverse cycle valve On when heating.
3.3. Thermostat communication settings
The communications format must be set in accordance with Modbus RTU standard settings:
•Baud rate 19200
•8 Data bits
•Even parity bit
•1 Stop bit
•TZT-100 modbus device address 7
•SAT-3 modbus device address 8
•The thermostat should be configured for 1-stage operation
Refer to the thermostat installer manual for procedures to check and adjust the settings in a SAT-3 or
TZT-100 thermostat.
4. Connecting to external devices using Modbus RTU over RS485
The UC8 provides a serial communications port (terminals A1 & B1) for RS485 type signals and wiring.
Full monitoring and control are available through this port. The communications protocol used is
Modbus RTU.
For more information refer to document “Temperzone UC8 –Modbus RTU serial communications”.

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 10 of 27
5. Connecting the indoor unit
During the first 30 seconds after mains power to the outdoor unit is switched on the UC8 controller
searches for a connection to an indoor unit. The indoor unit must send a reply to the outdoor unit
withing that first half minute. The outdoor unit will not continue attempting to contact the indoor unit
if no reply is received from the indoor unit within those first 30 seconds.
To ensure the indoor unit is ready to reply to the outdoor unit it is important that power to the indoor
unit must be applied either at the same time, or before, the outdoor unit.
5.1. Making a reliable connection between the outdoor- and indoor- unit
In most split air-conditioning installations the UC8 controller in the outdoor unit communicates with
an IUC (indoor unit controller) in the indoor unit. For reliable operation the connection should be
made using a shielded twisted pair cable. The twisted pair wires must be used for signals A and B. The
cable shield can be connected to the 0V terminal at the UC8 only.
Using a shielded twisted pair cable helps to reduce electrical interference from other nearby cabling:
•the cable shield reduces interference from electric fields generated by mains voltages
•using a twisted pair of wires reduces interference from magnetic fields that surround any
cables that carry electrical currents
IMPORTANT: The communications ports on the UC8 and on the IUC use the unit earth as reference;
the ports are not electrically isolated. For that reason it is important that there is a direct and solid
earth connection between the outdoor- and the indoor- units.
5.2. Connecting 1 outdoor unit to 1 indoor unit
The diagram below shows standard connections between outdoor- and indoor- units.

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 11 of 27
5.3. Connecting 1 outdoor unit to 2 indoor units
The diagram below shows how to connect one outdoor unit to two indoor units. Refer to the IUC
manual for the required IUC DIP switch settings.
Operation of the two indoor units is always identical, they cannot be controlled individually.
6. Capacity control
OSA units incorporate an inverter compressor that provides variable capacity. The following
paragraphs provide details on the available capacity control options.
Capacity at start-up
During the first 2 minutes after starting the capacity is fixed to 33% of unit rated capacity. After this
initial period normal capacity control commences.
Capacity control options
The following options are available for control of unit capacity:
•0-10V analogue voltage on input VC.
•Automatic with a SAT-3 or a TZT-100 room thermostat.
•Modbus RTU serial communications.
•Automatic based on supply air temperature.
6.1. 0-10V control
Capacity can be controlled with a 0-10V analogue control voltage from an external control device. The
unit must not connect to a SAT-3 nor to a TZT-100 room thermostat, must not be controlled with
Modbus RTU serial communications, and must not be configured for automatic control of the
evaporating / condensing temperatures.
Control voltage VF
Capacity
0V to 2V
Minimum
2V to 10V
Capacity varies approximately linearly as a function of the control voltage
10V
Maximum
Note: Switching off and on of the compressor is not controlled by the capacity signal.
6.2. Supply air temperature control
For information how to enable supply air temperature control refer to chapter 10.4.

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 12 of 27
6.3. Automatic control with SAT-3 or TZT-100 thermostat
An OSA unit connected to a SAT-3 or TZT-100 room thermostat automatically varies capacity in order
to make the room temperature equal to the selected setpoint temperature and then keep the room
temperature constant.
This means that, when the room temperature is equal to the selected setpoint, the unit does not
necessarily turn off but instead often continues operating to deliver the capacity necessary to keep
the room temperature constant. For example, it may happen that on a warm summer afternoon, with
the room temperature equal to setpoint, the unit may still need to continuously deliver cooling
capacity to match the heat load. Should the room temperature move to more than 0.3°C past setpoint
then the thermostat will stop the compressor.
The automatic capacity control function operates with conservative reaction speeds. This is necessary
to enable the function to work effectively over a wide range of applications. However, the function
may be too reactive in applications where there is a large mismatch between the unit capacity and
the room load. Typically this can occur in situations where a unit can deliver much more capacity than
is needed for the space. At the other end of the spectrum the response of the unit may sometimes
seem slow and sluggish.
6.4. Modbus RTU control
For detailed information on Modbus RTU serial communications refer to document “Unit controller 8
(UC8) Modbus RTU communications”.
An example for control of the compressor on/off, cooling/heating, indoor fan speed and unit capacity
(default values in bold letters):
Modbus register
Function
Values
101
Control-enable register
195
102
Compressor off / on
0 = Off 1 = On
103
Cooling / Heating
0 = Cooling 1 = Heating
108
Indoor fan speed
Stop 0
Low speed 100
Medium speed 550
High speed 1000
109
Capacity
Minimum 0 to 20
50% 50
100% 100
Notes:
1. Before switching the compressor on always first write to register 103 to select cooling or
heating. If this sequence is not adhered to then the unit may already have started when the
desired mode is changed. The result would be that the compressor would first continue to
operate for the minimum run time of 2 minutes (in the undesirable mode), followed by a 10-
minute-long mode change-over delay, and then finally re-start in the desired mode.
2. Switching the compressor on and off is controlled with register 102 and not by the capacity in
register 109. When the compressor is running then a capacity request of 0% provides
minimum capacity.

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 13 of 27
6.5. Oil recovery (oil flush) cycles
If the unit operates on low capacity for longer than 1 hour and 40 minutes the controller will perform
an oil recovery cycle. Oil recovery cycles are necessary to ensure sufficient lubricating oil returns to
the compressor. An oil recovery cycles takes 1 minute. During this one-minute the compressor speed
is increased and the EEV is directed to open.
It is possible to change the interval between oil recovery cycles (normally 1 hour and 40 minutes). It is
also possible to disable oil recovery cycles. If this is required contact temperzone customer service.
7. Dry mode (de-humidification)
OSA models provide three options for cooling mode:
Mode
Indoor fan speed
Standard cooling
Fixed
High-efficiency cooling
Variable
Dry cooling (de-humidification)
Variable
•Standard cooling mode:
This is the default mode. In this mode the controller does not actively control the indoor coil
temperature. De-humidification occurs only when the indoor coil temperature (= the refrigerant
evaporating temperature) is below the dew point. Under normal operating conditions the indoor fan
speed is kept equal to the speed requested by the thermostat.
Standard cooling mode is suitable for installations where indoor airflow must remain constant and/or
when de-humidification is not required.
•High efficiency cooling mode:
The UC8 controller must be allowed to vary the indoor fan speed to obtain an indoor coil temperature
for optimum unit duty and efficiency. Note that in this mode the indoor fan speed can differ from the
speed requested by the thermostat. De-humidification occurs only when the indoor coil temperature
is below the dew point.
High efficiency cooling mode may be unsuitable for installations where indoor airflow must remain
constant.
•Dry cooling mode (de-humidification):
The UC8 controller must be allowed to vary the indoor fan speed to obtain an indoor coil temperature
to that is below the dew point. The indoor fan speed can differ from the speed as requested by the
thermostat.
Dry cooling mode may be unsuitable for installations where indoor airflow must remain constant.
7.1. Dry mode and the SAT-3 thermostat
Refer to the SAT-3 installer and user manuals for configuring the SAT-3 thermostat.
To operate a unit in dry mode: Select cool + dry or auto cool / heat + dry, start the unit in cooling
mode. Select fan auto-speed (the word AUTO shows on the fan display).

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 14 of 27
7.2. Dry mode and the TZT-100 thermostat
To configure the TZT-100 thermostat for dry mode:
•Press-and-hold the O/RIDE button for 15 seconds until the PIN code is shown (88:15).
•Use the Up/Down buttons to select the correct PIN code (default is 88:21), then press O/RIDE
again. The thermostat is now in installer mode.
•Press O/RIDE a number of times until the screen shows Fn.
•Press the Up/Down buttons to select the correct option. The options are:
o-- manually select heating / cooling
oH heating only
oC cooling only
oA heating / cooling / auto
od- manually select heating / cooling / cooling with dry mode
odC cooling / cooling with dry mode
odA heating only / cooling only / cooling with dry mode / auto with dry mode
•After selecting the desired option press MODE to exit from installer mode.
To operate a unit in dry mode: Select cool + dry or auto cool / heat + dry, start the unit in cooling
mode. Select fan setting “Low-Med-High”.
8. Indoor fan control
Temperzone OSA units normally connect to a matching indoor unit, models ISD. For convenience any
of the following inputs can be used to control the fan in the indoor unit:
•IUC inputs Hi-Me-Lo (inputs for voltage-free contacts, note 1)
•UC8 inputs HI-ME-LO (24V AC or 12V to 24V DC signals, note 1)
•UC8 input VF (0-10V, note 1)
•SAT-3 or TZT-100 room thermostat (note 2)
•Modbus RTU serial communications using RS485 wiring (note 3)
Notes:
1. If the unit is not controlled by Modbus RTU serial communications or SAT-3 or TZT-100 then
the UC8 automatically selects the input that requests the highest indoor fan speed.
2. If control is by SAT-3 or TZT-100 thermostat then signals on IUC inputs Hi-Me-Lo and on UC8
inputs HI-ME-LO and VF have no effect.
3. If control by serial communications is used then all other control options are disabled. For
more information refer to document “Temperzone UC8 Modbus communications”.
Some installations do not permit indoor fan speed to vary from the requested speed at any time.
For such installations the indoor fan can be controlled directly by an external controller or the fan may
be hardwired to run at a constant fixed speed.
If the UC8 is not used to control the indoor fan then it is the responsibility of the system- designer
and -installer to ensure proper and safe operation of the indoor fan, and the system as a whole,
under all operating conditions.

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 15 of 27
8.1. Indoor fan speed adjustment
The IUC inside the indoor unit controls a variable speed indoor fan using a 0-10V signal from output
V1. Factory default settings for the output voltage provided on output V2 are:
•Off 0V
•Low 5V
•Medium 6.5V
•High 8V
It is possible to adjust these voltages. If the unit is controlled by a SAT-3 thermostat then placing the
SAT-3 in fan speed setup mode will allow adjustment via the keypad on the SAT-3 thermostat. For
more information on this refer to the SAT-3 installer manual.
If the unit is not controlled by a SAT-3 thermostat then by default the fan speed settings are
determined by DIP switch settings on the IUC. For more information refer to the manual for the IUC.
In installations where access to the indoor unit is restricted it could be more convenient to adjust the
indoor fan speed settings from the UC8 in the outdoor unit. If this is the case then turn on UC8 DIP
switch 5, remove power and then re-apply power to the unit. After that the fan speed settings can be
adjusted as follows:
To adjust the fan high speed setting:
Hold down UC8 pushbutton SW3 until the display shows the letter “H”, then release the
button. The UC8 will enter “fan high speed setup mode”. The display will show the current
high-speed voltage setting, e.g. “8.0” and the indoor fan will run accordingly.
Use the pushbutton to change the voltage from 3.0 to 10.0V in steps of 0.5V.
When the desired fan high speed has been set then wait 30 seconds, the controller will save
selected setting.
To adjust the fan low speed setting:
Hold down UC8 pushbutton SW3 until the display shows the letter “L”, then release the
button. The UC8 will enter “fan low speed setup mode”. The display will show the current low
speed voltage setting, e.g. “5.0” and the indoor fan will run accordingly.
Use the pushbutton to change the voltage from 1.0 to 8.0V in steps of 0.5V.
When the desired fan low speed has been set then wait 30 seconds, the controller will save
selected setting.
Notes:
1. It is allowed to select a low speed voltage equal to the high speed voltage. In effect the fan
then operates as a fixed-speed fan at the selected control voltage.
2. Fan medium speed voltage is always halfway between the low and high control voltages.
3. Fan off voltage is always 0V.

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 16 of 27
In most installations the factory settings provide an adequate range of indoor airflow whilst avoiding
risk of indoor coil frost, water carry-over and excessive noise. Care must be taken when changing the
indoor fan speed control voltages:
•To ensure the indoor fan always starts it is recommended to avoid ‘low speed voltage’ settings
below 2V.
•To avoid increased risk of frost protection trips and unit lock-out do not set the fan low speed
so low that the evaporating temperature can fall below 0°C.
•To avoid risk of water leaking from the supply air vents and corrosion of ducting do not set the
fan high speed so high that moisture that may have condensed on the fins of the indoor coil is
blown off the coil and into the supply air duct.
•Reducing the high fan speed settings may help when there’s significant noise from supply air
vents.
•To reduce risk of ‘over-condensing’ during heating mode, which in turn may cause supply air to
feel relatively cool, or even water freeze protection trips, avoid very high fan speed settings.
8.2. Translation from 0-10V fan control input signal VF to a fan output signal
Input VF on the UC8 can be used for a 0-10V control signal for the indoor fan.
If the indoor fan speed is controlled using a control voltage applied to input VF then that input voltage
is translated to a corresponding output voltage. The translation ensures that the UC8 programmed
fan speed settings are obeyed.
Translation from 0-10V input VF to a voltage on output V2 is as follows, assuming the default settings
of 5V for low speed to 8V for high speed.
Input VF Output V2 Fan
0.0V to 0.99V 0V Off
1.0V to 1.49V 0 or 5V Off or Low speed, whichever is currently the case
1.5V to 9.50V 5V to 8V Low speed to High speed
9.5V to 10.0V 8V High speed
If above translation is undesirable then one could follow the procedure described above to change
the minimum and maximum voltage settings, or one could bypass the UC8 and apply the external
control voltage directly to the indoor fan.

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 17 of 27
9. Display messages
The following messages can be seen on the LED display.
Display
Meaning
Notes / factory setting
UC8
Controller name
Shown only after power-on
6.1.2-55
Software version and build number
HDE5A61E
Software identification code
dELAY
Start-up random delay time
●
Ready, normal operation
−
Unit is OFF by Remote On/Off signal
HOLd
The compressor is held-on or held-off by a timer
diFF-P
The pressure differential is too high for the inverter
compressor to start

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 18 of 27
Pressures and temperatures and other information can be observed on the controller display while
the unit is in normal mode or in commissioning mode. This is available regardless whether the
compressor is on or off. Use short button presses to cycle the display through the options. After 2
minutes the display automatically returns to a flashing dot (or ‘c’).
Display
Meaning
Units
● or c
Normal mode (default)
-
SLP
Compressor suction line pressure
kPa
Et
Evaporating temperature
°C
SLt
Compressor suction line temperature
°C
SSH
Compressor suction side superheat
K
dLP
Compressor discharge line pressure
kPa
Ct
Condensing temperature
°C
dLt
Compressor discharge line temperature
°C
dSH
Compressor discharge side superheat
K
ICEt
Outdoor coil de-icing sensor temperature
°C
CAP
Unit capacity (duty)
%
EE1
Electronic expansion valve 1 opening
%
EE2
Electronic expansion valve 2 opening
%
Add
UC8 Modbus RTU slave address
-
● or c
Back to button press 0
-
Pressures are shown in kPa. Divide by 6.895 (roughly 7) to convert to PSI.
Temperatures are shown in whole degrees Celsius. If the indicated temperature is below 0°C then a
minus sign is shown before the value. The condensing- and the evaporating-temperature are
converted from the pressure readings.
If a measurement is not available then the display shows a dash symbol (-).

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 19 of 27
10. Special modes
The UC8 offers several options for making modifications to the operation of the unit.
Operating the pushbutton in level 1:
•Apply power to the unit and wait until the power-on sequence is completed.
•The compressor must be off and there must be no request to start.
•Hold down pushbutton SW3. After two seconds the display will show the letter t. Continue
pressing the pushbutton until the display shows the character of the desired mode, then
release the button.
Operating the pushbutton in levels 2, 3 and 4:
•In levels 2, 3 and 4 use short button presses to move between options.
•Short presses must be given before the display has shown the same character four times or
else the option shown is selected.
•Therefore, to select an option do not press the button. The display will show the character
four times, then the controller enters the selected mode.
Level 1.
Option
Factory default
t
Start factory test mode
Off
c
Start or end commissioning mode
Off
H
Adjust the indoor fan high speed voltage
5.0V
L
Adjust the indoor fan low speed voltage
8.0V
2.
Advance to level 2.
.
Return to normal mode
Level 2.
A
Change the UC8 Modbus RTU slave address
44
r
Indoor fan fixed speed
Off (0)
o
Turn the thermostat on/off with the remote on/off signal
Off (0)
Y
Enable evaporating / condensing temperature control
Off (0)
3.
Advance to level 3.
.
Return to normal mode
Level 3.
J
Outdoor fan common chamber
No (0)
B
Adjust the serial communications baud rate
19200 (2)
P
Adjust the serial communications parity & stop bit setting
Even parity, 1 stop bit (2)
4.
Advance to level 4.
.
Return to normal mode
Level 4.
E
Select the compressor model
n
Select the expansion valve operating mode
.
Return to normal mode

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 20 of 27
10.1. Factory test mode: t
In factory test mode the controller activates the various control board output signals one by one, with
a pause between each step. When the test sequence is complete the controller automatically returns
to normal mode.
10.2. Commissioning mode: c
During commissioning mode delay times are reduced:
•Minimum On-Off time (‘Run’-time) 90 seconds
•Minimum Off-On time (‘Off’-time) 20 seconds
•Minimum On-On time (‘Cycle’-time) 1 minute
•Cooling to heating change-over time 1 minute
•Heating to cooling change-over time 1 minute
Commissioning mode ends automatically after 30 minutes. It is also possible to manually end
commissioning mode either by cycling mains power off and on again, or by again using the
pushbutton and select option ‘c’. When commissioning mode ends the controller returns to normal
mode.
10.3. Compressor selection mode: E
IMPORTANT: Always ensure the correct compressor model is selected!
If an incorrect selection is made it is likely to cause the unit to malfunction and could lead to
permanent damage to the compressor.
Unit model
Compressor model
Display
OSA 171 RLS
YPV030LT-3X9 Copeland
P1-Y030L
OSA 171 RLT
YPV030LT-4X9 Copeland
P3-Y030Lt
OSA 211 RLT
YPV038LT-4X9 Copeland
P3-Y038L
OSA 251 RLT
YPV050ST-4X9 Copeland
P3-Y050S
OSA 351 RLT
AVB66FT2MT SCI
P3-AUb66
10.4. Supply-air temperature control option: Y
OSA + ISD installations can provide automatic control of the supply air temperature. Available
selections are:
•0: Disable supply air temperature control (default value)
•1: Enable supply air temperature control