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Temperzone Troubleshooting Guide for UC7 Controller
Troubleshooting Guide for UC7
Document revision : 3
Date: 19 October 2012
Index
1.
Cautions ........................................................................................................................................... 2
2.
Items to check before starting .......................................................................................................... 2
3.
Troubleshooting procedure .............................................................................................................. 3
4.
Normal display messages ................................................................................................................ 4
5.
Fault messages ................................................................................................................................. 5
6.
Fault codes. ...................................................................................................................................... 6
7.
Safety timer durations ...................................................................................................................... 8
8.
Protection functions ......................................................................................................................... 9
High pressure protection (HP) .......................................................................................... 9
Low pressure protection (LP)............................................................................................ 9
Indoor coil frost protection................................................................................................ 9
High temperature protection ............................................................................................. 9
High suction line temperature protection ........................................................................ 10
Low discharge superheat protection................................................................................ 10
High discharge superheat protection ............................................................................... 10
Freeze protection ............................................................................................................. 10
Overload protection ......................................................................................................... 11
9.
Lock-out ......................................................................................................................................... 11
10.
Unit log .......................................................................................................................................... 12
11.
Expansion valve types and DIP switch settings ............................................................................ 13
Page 1 of 13
Temperzone Troubleshooting Guide for UC7 Controller
1. Cautions




Turn off mains power before opening the electrical panel of a unit.
When disconnecting and connecting connectors hold them by the housing. Do not pull on the wires.
Use as little force as possible when replacing electronic circuit boards.
Never pull on individual electronic components.
2. Items to check before starting





Thoroughly investigate the customer complaint.
Does the unit run at all?
Check mains power is properly connected and is the voltage correct.
Check control wires between indoor and outdoor units and to the thermostat or other controller.
Take careful note of any information shown on the controller board display.

Hydronic units will not run the compressor until:
o The water pump runs OK.
o The water flow switch is closed.

Chiller units will not run the compressor until:
o The water pump runs OK.
o The water flow switch is closed.
o The supply water temperature is above +2°C.
Page 2 of 13
Temperzone Troubleshooting Guide for UC7 Controller
3. Troubleshooting procedure
Unit does not run
Is power light
on?
No
Yes
Display shows
flashing dash
(▬)?
Yes
No
Display shows
flashing dot (●)?
No
Yes
Display shows
“HOLd”?
Yes
No
Display shows
“dr”?
Yes
No
Display shows
other letters
and/or numbers
(not listed under
normal
operation)?
Yes
No
Check:
 Mains power is supplied to the unit.
 Control circuit breaker is on.
 Mains wiring and connectors are OK.
 230V AC mains is present across the L and N
terminals.
 Fuse on controller board; replace board if fuse is
blown.
Remote On/Off input is open circuit:
Connect input On to G.
Check COMP input signal:
 With a switched thermostat or BMS using the COMP
input: Check 24V AC is present between COMP and
C2.
 With TZT-100 thermostat: Check the thermostat
Yes
shows a small satellite dish symbol on the display.
Check thermostat shows Cooling or Heating (not
flashing).
 With communicating BMS: Refer to document
“Temperzone UC7 modbus communications”.
Check CMC output signal:
 Check Comp light is on.
 Check wiring from CMC contacts to the compressor
contactor.
 Check compressor contactor and circuit breaker.
A safety timer is active:
Wait until the safety timer expires.
DRED energy restriction is active:
 Wait until DRED energy restriction condition ends.
If DRED function is not required:
 Air-to-air units: Inputs D1, D2, D3 should be open
circuit (Note: D1 may be used to control Quiet mode.)
 Hydronic units: Input D3 should be open circuit.
 Chillers
: Inputs D1, D2, D3 should be open
circuit
The controller has detected a fault.
Refer to sections “Fault messages” and “Fault codes”.
Contact Temperzone service agent.
Page 3 of 13
Temperzone Troubleshooting Guide for UC7 Controller
4. Normal display messages
The UC7 controller display may show one or more of the following during normal operation.
Table 1: Normal controller display messages
Display
Meaning
UC7 4.9
Controller model number (UC7) and software version
(shown only after power-on)
0
(flashing)
dELAY
The expansion valve is initialising
(shown only after power-on)
The unit waits for a random start-up delay time
(up to about 30s, occurs only after power-on)
●
(flashing)
−
(slowly flashing)
Normal operation
Unit is OFF by Remote On/Off signal
dE-ICE
De-icing the outdoor coil
c
Commissioning mode (automatically expires after 30 minutes)
t
Test mode
HOLd
The compressor is held-on or held-off by a safety timer
dr
DRED energy consumption restriction is active
(automatically expires after about 1 minute)
It is possible to use the controller display to view system pressures and temperatures. This is available
with the unit in normal mode and in commissioning mode and regardless whether the compressor is
on or off. It is not available when the controller is reporting a fault.
To view pressures and temperatures:
Repeatedly press the pushbutton to cycle the display through the options (in a round robin fashion).
After 2 minutes the display will automatically return to a flashing dot (or “c”).
Table 2: Pressure and temperature display messages
Button press
Display
Meaning
Units
0
● or c
1
SLP
2
Normal mode (default)
Suction line pressure
kPa
Et
Evaporating temperature
°C
3
SLt
Suction line temperature
°C
4
SSH
Suction side superheat
K
5
dLP
Discharge line pressure
kPa
6
Ct
Condensing temperature
°C
7
dLt
Discharge line temperature
°C
8
dSH
Discharge side superheat
K
9
● 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 degrees Celsius (°C). If the indicated temperature is below 0°C then a
minus sign is shown before the value. Note: If the unit has one or two pressure transducers then the
condensing and/or evaporating temperatures shown are converted from pressure readings.
Page 4 of 13
Temperzone Troubleshooting Guide for UC7 Controller
5. Fault messages
Table 3: Fault messages
Display Meaning
LP
HP
Possible cause
Possible remedy
Low pressure
protection
Check for refrigerant leaks.
Expansion valve is closed.
High pressure
protection
Faulty transducer cable.
Faulty transducer.
Service valve is closed.
Outdoor fan does not start
(cooling mode).
Indoor fan does not start
(heating mode).
Unit is overcharged.
Fix leak, evacuate unit, then recharge.
Check valve coil is properly fitted onto the
valve body.
Check DIP switch settings.
Repair wiring to the valve.
Replace expansion valve.
Repair transducer cable.
Replace transducer.
Open service valves.
Repair fan or fan wiring. Repair if required.
Expansion valve is closed.
HI-t
FROSt
HI-SL
High
temperature
protection
Indoor coil frost
protection
Repair fan or fan wiring. Repair if required.
Remove excess refrigerant charge.
Faulty transducer cable.
Faulty transducer.
Check DIP switch settings.
Repair wiring to the valve.
Replace expansion valve.
Repair cable to the transducer.
Replace transducer.
Service valve is closed.
Open service valves.
Insufficient refrigerant.
Add refrigerant.
Faulty discharge line
temperature sensor.
Problem with expansion valve
Replace sensor.
Air filter blocked.
Clean or replace air filter.
Indoor dampers closed.
Check dampers and damper controls.
Indoor fan speed too low.
Increase indoor fan speed.
Indoor fan motor and/or speed
controller fault.
Return air temperature too low.
Replace indoor fan motor and/or speed
controller.
Ensure unit is not operated in cooling mode
with low return air temperature.
Add refrigerant.
High suction line Insufficient refrigerant.
temperature
Very high room temperature
protection
(cooling mode).
Very high outdoor ambient
temperature (heating mode).
Faulty suction line temperature
sensor.
Page 5 of 13
Check expansion valve operation (superheat)
Reduce indoor fan speed (temporarily).
Ensure unit is not operated in heating mode
with very high outdoor ambient
temperature.
Replace sensor.
Temperzone Troubleshooting Guide for UC7 Controller
Display Meaning
Possible cause
Possible remedy
Lo-dSH
Unit is overcharged.
Remove excess refrigerant charge.
Discharge line temperature
sensor not properly fitted.
Faulty discharge line
temperature sensor.
Incorrect expansion valve
selection
Loss of refrigerant.
Correctly fit the temperature sensor.
HI-dSH
OL
Low discharge
superheat
protection
High discharge
superheat
protection
Overload
protection
Faulty discharge line high
pressure transducer.
Incorrect expansion valve
selection
Indoor fan is overloaded.
Outdoor fan is overloaded.
Replace sensor.
Check DIP switch settings for switches 7, 8, 9
and 10
Find refrigerant leak and repair. Replace
refrigerant with correct charge.
Replace transducer.
Check DIP switch settings for switches 7, 8, 9
and 10
Check indoor fan. Check airflow is not
obstructed.
Check outdoor fan. Check airflow is not
obstructed.
Compressor overheated.
Wait until compressor has cooled down
sufficiently. Check system has adequate
refrigerant charge. System design must
ensure adequate return of compressor
lubricating oil.
Check wiring and connections to Repair wiring.
inputs IN#2, COMP and C2.
6. Fault codes.
Table 4: Fault codes
Display Fault
F10
F11
F12
F13
F14
Possible cause
Possible remedy
Incorrect DIP switch settings.
Change DIP switch settings.
Loose wiring between UC7 board and
outdoor fan speed controller board.
No power to outdoor fan speed
controller.
Faulty outdoor fan speed controller
board.
Incorrect DIP switch settings.
Repair wiring.
Loose wiring between UC7 board and
indoor fan speed controller board.
No power to indoor fan speed
controller.
Faulty indoor fan speed controller
board.
High pressure transducer. Refer to “HP”.
Low pressure transducer. Refer to “LP”.
Suction line
Loose connection.
temperature
Faulty temperature sensor.
sensor
Repair wiring.
Outdoor fan
(no serial
communications)
Indoor fan
(no serial
communications)
Page 6 of 13
Ensure power is present.
Replace outdoor fan speed
controller.
Change DIP switch settings.
Ensure power is present.
Replace indoor fan speed
controller.
Repair connections.
Replace sensor.
Temperzone Troubleshooting Guide for UC7 Controller
Display Fault
F15
F16
F17
F18
F19
F20
F21
F22
F23
F24
F25
F26
F27
F28
F29
F30
F31
F32
F33
Possible cause
Possible remedy
Discharge line
temperature
sensor
De-Ice temperature
sensor
Loose connection.
Repair connections.
Faulty temperature sensor.
Replace sensor.
Loose connection.
Repair connections.
Faulty temperature sensor.
Replace sensor.
Outdoor coil
temperature
sensor
Indoor coil
temperature
sensor
Ambient
temperature
sensor
Superheat
unknown
Loose connection.
Repair connections.
Faulty temperature sensor.
Replace sensor.
Loose connection.
Repair connections.
Faulty temperature sensor.
Replace sensor.
Loose connection.
Repair connections.
Faulty temperature sensor.
Replace sensor.
Thermostat
(no serial comms)
System 1 or BMS
(no serial comms)
System 2
(no serial comms)
System 3
(no serial comms)
System 4
(no serial comms)
Invalid DIP switches
setting
Invalid fan
selection
Invalid economiser
selection
Microcontroller
temperature too
high
Supply voltage out
of bounds
A slave unit reports
a fault
0-10V input
Check: low pressure transducer, suction line temperature sensor, high
pressure transducer, discharge line temperature sensor, outdoor coil
temperature sensor, indoor coil temperature sensor.
Loose wiring.
Repair connections.
Loose wiring.
Repair connections.
Master unit or BMS controller off.
Turn master unit or BMS on.
Master unit or BMS communications
intermittent.
Loose wiring.
Incorrect DIP switch settings.
Loose wiring.
Incorrect DIP switch settings.
Loose wiring.
Ensure BMS communicates at least
once every 5 minutes.
Repair connections.
Check DIP switch settings.
Repair connections.
Check DIP switch settings.
Repair connections.
Incorrect DIP switch settings.
Check DIP switch settings.
Check DIP switch settings.
Check DIP switch settings.
Check DIP switch settings.
Wait until the unit has cooled down.
Find cause of extremely high temperature in the electrical compartment.
Check that 230V AC mains power supply voltage is stable.
Check slave units.
Check 0-10V input board is properly and correctly plugged in. Replace 0-10V
input board if faulty.
Refer to “high discharge superheat” (shown as “HI-dSH”)
Page 7 of 13
Temperzone Troubleshooting Guide for UC7 Controller
Display Fault
F34
Problem with
readings from the
pressure
transducers
F35
Reverse cycle valve
F36
Invalid DIP switch
setting on TZT-100
thermostat
Possible cause
Possible remedy
Transducer wires swapped.
Correct transducer wiring.
Transducers fitted to wrong pipe.
Swap transducers.
Incorrect transducer type.
Fir correct transducer.
Incorrect DIP switch 2 setting.
Check DIP switch 2 setting.
Expansion valve closed.
Repair EEV wires.
Faulty transducer.
Replace transducer.
Loose wiring.
Repair wiring.
Faulty reverse cycle valve.
Replace reverse cycle valve.
The TZT-100 thermostat DIP switches must be set to:
 1-stage operation
 heat-pump equipment type
 the reverse cycle valve must be on when the thermostat requests
heating mode
7. Safety timer durations
Safety timer
Duration
Unit start-up delay (after mains power-on)
2 minutes
Minimum compressor run-time
(On-to-Off duration)
1 minute 30 seconds
Minimum compressor off-time
(Off-to-On duration)
1 minute 30 seconds
Minimum compressor cycle-time
(On-to-On duration)
6 minutes
(a maximum of ten compressor starts per hour)
Hydronic unit compressor start delay (to allow
water flow pump to start and water valve to open)
45 seconds
HP protection
3 minutes
LP protection
3 minutes
High discharge temperature protection
3 minutes
Frost protection (indoor coil)
10 minutes
Freeze protection (hydronic units)
3 minutes
High suction line temperature/pressure protection
3 minutes
Low discharge superheat protection
3 minutes
Overload protection
3 minutes
Page 8 of 13
Temperzone Troubleshooting Guide for UC7 Controller
8. Protection functions
High pressure protection (HP)
Protects a unit from excessively high refrigerant pressure.
Conditions: Unit with HP switch: When the switch activates (open circuit).
Unit with high pressure transducer: When compressor discharge pressure exceeds 4237
kPa (614.5 PSI, equivalent to +66°C condensing temperature).
Hydronic reverse cycle units only (these units switch the high pressure transducer to
the suction line when heating): When the indoor coil temperature exceeds 56°C.
Note: A faulty pressure transducer is also reported as an HP fault.
Low pressure protection (LP)
Protects a unit from excessively low refrigerant pressure.
Conditions: Unit with LP switch: As soon as the switch activates (open circuit).
If a low pressure transducer is connected there are two levels:
Transient level: When pressure is below 114 kPa (16.5 PSI, equivalent to -35°C).
Normal level: When pressure is below 228 kPa (33.0 PSI, equivalent to -25°C).
Notes: The transient level is always applied.
The normal level is applied when more than 3 minutes have expired since the compressor
started, or more than 3 minutes after the end of a de-ice cycle.
A faulty pressure transducer is also reported as an LP fault.
Indoor coil frost protection
Protects a unit from forming too much ice on the indoor coil. Applied only when a unit is cooling in
normal mode, not applied when a unit is de-icing the outdoor coil.
The frost protection function activates when start conditions persists for longer than the frost-protect
delay time. The frost-protect delay time depends on whether the unit has run during the last two
hours or not:
The compressor has run during the last 2 hour period: protect delay time 2½ minutes.
The compressor has been off for more than 2 hours : protect delay time 4 minutes.
Conditions: When T(evaporating) is below -8°C for longer than the frost-protect delay time.
When T(evaporating) is below -4°C and T(suction line) is below +4°C for longer than the
frost-protect delay time.
If T(evaporating) is not known to the controller: When T(suction line) is below -10°C for
longer than the frost-protect delay time.
High temperature protection
Protects the compressor from overheating.
Conditions: When the compressor discharge line temperature exceeds:
+115°C for longer than 2 seconds or
+105°C for longer than 1 hour.
For hydronic units with electric heating only:
When the supply air temperature sensor (connected to input AMB) exceeds
+75°C for longer than 2 seconds.
Page 9 of 13
Temperzone Troubleshooting Guide for UC7 Controller
High suction line temperature protection
Protects the compressor motor from overheating.
Conditions: When T(suction line) exceeds +25°C
and/or T(evaporating) exceeds +22°C
and/or P(suction line) exceeds 1428 kPa (207 PSI, equivalent to +22°C)
for longer than 5 minutes.
Note: If the unit has a digital scroll compressor then high suction line temperature protection is
applied only when capacity is at 100%.
Low discharge superheat protection
Protects a unit from prolonged flooding of the compressor. Applied only when the unit is operating in
normal mode, not applied when a unit is de-icing the outdoor coil.
Conditions: When discharge superheat is below 10K for longer than 20 minutes.
Notes: If the unit has a digital scroll compressor then low discharge superheat protection is applied
only when unit capacity is at 90% or higher.
Discharge superheat is defined as the difference between the compressor discharge line
temperature and the condensing temperature.
High discharge superheat protection
Protects a unit from prolonged running with a lack of refirgerant. Applied only when the unit is
operating in normal mode, not applied when a unit is de-icing the outdoor coil.
Conditions: When discharge superheat is above 38K for longer than 45 minutes.
Note: Discharge superheat is defined as the difference between the compressor discharge line
temperature and the condensing temperature.
Freeze protection
Protects against freezing of the circulating water. This function has start conditions that depend on
the type of unit.
For hydronic reverse cycle units:
Applied only while heating.
Conditions: When T(evaporating) is below -6°C for longer than 30 seconds.
When T(evaporating) is below -2°C and T(suction line) is below +3°C for longer than 30
seconds.
For chiller units:
Applied only while cooling.
Conditions: When T(evaporating) is below -12°C for longer than 5 seconds.
When T(evaporating) is below -2°C and T(suction line) is below 0°C for longer than 5
seconds.
Page 10 of 13
Temperzone Troubleshooting Guide for UC7 Controller
Overload protection
Protects various components of the system such as the compressor, indoor and outdoor fan motors.
Conditions:
When the overload input signal becomes active.
The UC7 controller has a number of options for the overload input signal:
Unit with LP switch and where the COMP input is used: In these units any overload switches are
wired in series with the COMP input signal. In this case when an overload signal is active the unit will
not start the compressor but the controller display will not show a fault.
Unit with LP switch and TZT-100 thermostat (or communicating BMS): Overload switches are wired
to the COMP input. If the COMP input becomes inactive the display will show the “OL” message.
Unit with low pressure transducer: Overload switches are wired to the IN#2 and/or the COMP input.
If the IN#2 and/or the COMP input becomes inactive the display will show the “OL” message.
9. Lock-out
The controller counts the number of trip events for each of the safety functions.
All trip event counters are reset to zero when the thermostat calls for the compressor to be off.
If any of the following trip counters reaches the value 3 then the unit will be placed into lock-out
mode:
 HP
 LP
 High temperature protect
 Frost protect
 High suction line temperature protect
 Low discharge superheat protect
 Freeze protect
During lock-out mode the compressor is not allowed to run. The display will show which protection
caused the lock-out and the fault relay is active.
Lock-out mode can be cleared only by removing and then re-applying mains power to the unit.
When a unit was locked out and mains power is removed and then re-applied the display will show
the previous fault message for 45 seconds (after the normal start-up sequence). Then normal
operation resumes. This 45 seconds message display will repeat every time mains power is removed
and re-applied until the unit has completed at least one normal compressor-on - compressor-off
cycle.
Page 11 of 13
Temperzone Troubleshooting Guide for UC7 Controller
10. Unit log
The controller keeps an internal log of certain information. The log can be viewed as follows:
 Connect a USB to RS485 converter to a computer and to UC7 terminals A1 and B1 respectively.

On the computer start a simple communications program such as HyperTerm or TeraTerm.

Settings of the communications parameters must be: 115200 baud, 8 data bits, no parity bit, 1 stop
bit. The COM port number must be that of the USB to RS485 serial interface.

Switch power to the unit controller off.

Press the small push-button on the UC7 controller circuit board. While still holding down the pushbutton switch power to the unit on. Keep pressing (a few seconds) until the display on the controller
shows the letter P.

The computer screen will now show a small menu as shown here:
=============================
(C) COPYRIGHT 2011 Temperzone
UC7 bootloader
version 1.3
Please choose an option:
Download new software
- 1
Start normal operation
- 2
View unit log record
- 3
Disable write protection - 4
=============================

Choose “View unit log record” by pressing 3 on the computer keyboard.
Page 12 of 13
Temperzone Troubleshooting Guide for UC7 Controller

The unit log will now be displayed on the computer screen.
============================= Unit log record:
Hours
: 168
Minutes : 20
Cooling cycles : 61
Heating cycles : 7
De-ice cycles : 0
HP events
: 0
LP events
: 0
Frost events
: 0
Freeze events
: 0
High Temp events: 0
High S/L events: 0
Overload events: 0
Low DSH
events: 0
Power-on resets : 4
Watchdog resets : 0
Manual
resets : 1
Other
resets : 0
Indoor coil sensor
faults : 0
Outdoor coil sensor
faults : 0
Ambient temp sensor
faults : 0
Discharge line sensor faults : 0
Suction line sensor
faults : 0
De-Ice sensor
faults : 0
High pressure sensor faults : 0
Low pressure sensor faults : 0
High board temp
faults : 0
Normal operation starts now...


The unit controller will immediately resume the normal unit power-up procedure.
The information on the computer screen can be copied to any text document using normal selectcopy-paste procedures. The text document can then be saved for future reference, emailed to a
service centre, etc.
11. Expansion valve types and DIP switch settings
9
10
Electronic expansion valve type
How to recognise the valve type
OFF
OFF
Dunan DPF series
removable black coil
ON
OFF
Zhe Jiang Sanhua DPF series
non-removable metal coil
OFF
ON
Carel E2V series (& E3V series with unipolar coil)
removable red coil
ON
ON
Custom series
-
Below are images that will help to recognise the correct expansion valve used in the unit:
Dunan
Sanhua
Page 13 of 13
Carel
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