W3230 DC 12V Digital Temperature Controller – Wiring, Setup & Troubleshooting
The W3230 is a compact digital thermostat that measures temperature with an external NTC probe and automatically switches a relay to control heating or cooling equipment.
This guide is for the DC 12V version stocked by AuscomTech. It covers the power and relay connections, target temperature setting, heating and cooling modes, hysteresis, start delay, calibration and common troubleshooting.
W3230 Overview
The upper red PV display shows the temperature measured by the probe. The lower blue SV display shows the target or set temperature.
Outside the normal three-digit decimal display range, the controller may display temperature in whole degrees rather than 0.1°C increments.
Important Version & Load Information
W3230 controllers are also produced in 24V DC and 110–220V AC versions. These are different power-supply versions. Do not connect 24V or mains voltage to an AuscomTech 12V unit.
AuscomTech stocks the 12V version. Other W3230 supply-voltage versions may be available on request, but their power wiring must follow the markings on that specific controller.
The S1 and S2 terminals close together when the relay operates. Your load supply must therefore be wired through these contacts in series with the load. Simply connecting a device between S1 and S2 will not power it.
Relay capability depends on load type, switching voltage, inrush current, wiring, terminal condition and duty cycle. Motors, compressors, solenoids and some heaters can draw much more current at switch-on than during normal operation. Use suitable circuit protection and an external relay, contactor or other correctly rated switching device for substantial or high-inrush loads.
This support guide covers low-voltage DC wiring only. Do not use the diagrams below as instructions for switching 230V mains equipment.
Connections & Front Controls
Read the markings on the actual controller before wiring. On the stocked W3230 style, the main terminals are identified as +VCC, -GND, S1 and S2.
| Connection | Function | 12V Version |
|---|---|---|
| +VCC | Controller power input | Connect to +12V DC |
| -GND | Controller power return | Connect to 0V / supply negative |
| S1 | Relay contact | One side of normally-open relay switch |
| S2 | Relay contact | Other side of normally-open relay switch |
| Temperature Probe | Temperature measurement | NTC 10k probe, approximately 1m lead |
| Front Panel Item | Function |
|---|---|
| PV | Current measured temperature |
| SV | Target temperature |
| ▲ | Increase a value or move through menu choices |
| SET | Set target temperature, enter parameters and confirm selections |
| ▼ | Decrease a value or move through menu choices |
| OUT Indicator | Shows relay operation; normally steady when the relay is energised and flashing while a start delay is active |
| Restart / Standby Button | Front-panel power or restart function; behaviour can vary slightly between W3230 firmware revisions |
12V DC Wiring
Powering the Controller
Use a regulated 12V DC supply suitable for both the controller and any 12V load being powered from the same supply.
| 12V Power Supply | W3230 |
|---|---|
| +12V | +VCC |
| 0V / Negative | -GND |
Example: Switching a 12V DC Heater, Fan or Lamp
The relay contacts can be placed in series with the positive side of a low-voltage load circuit:
| Connection | Wire To |
|---|---|
| Power supply +12V | W3230 +VCC |
| Power supply negative | W3230 -GND |
| Power supply +12V | S1 relay terminal |
| S2 relay terminal | Load positive |
| Load negative | Power supply negative |
S1 and S2 are interchangeable for this simple relay circuit. When the W3230 calls for heating or cooling, the relay closes S1 to S2 and completes the load circuit.
The W3230 itself only needs enough 12V power for its electronics and relay coil. The load current flows through the relay contacts and must also be within the capability of the power supply, wiring, protection devices and switching hardware.
Basic Setup & Proof of Operation
Set the Target Temperature
- Connect the temperature probe and power the W3230 from 12V DC.
- Check that the red PV display shows a sensible temperature.
- Press SET once. The set temperature should flash.
- Use ▲ and ▼ to select the required temperature.
- Press SET again to confirm.
Simple Bench Test
For an easy proof-of-operation test, use a small 12V lamp, fan or other low-current load and temporarily set P5 delay to 0 minutes.
Set P0 to cooling mode and choose an SV temperature a few degrees below the current room temperature. Because PV is now above the cooling setpoint, the relay should energise. The OUT indicator should illuminate and the load should operate.
Raise the setpoint above the measured room temperature. The relay should release and the load should switch off.
Expected Result
The PV display should respond to temperature changes at the probe, the SV display should retain the selected target temperature, and the OUT indicator and connected load should follow the selected heating or cooling logic.
Advanced Parameter Menu
On the supplied W3230 documentation, hold SET for approximately five seconds to enter the parameter menu. Use ▲ and ▼ to choose a parameter, press SET to edit it, change the value with ▲ or ▼, then press SET again to confirm. The controller also exits the menu after a period without button activity.
| Parameter | Function | Use |
|---|---|---|
| P0 | Heating / Cooling | H = heating, C = cooling |
| P1 | Hysteresis / Return Difference | Sets the temperature difference between relay switch-on and switch-off; stocked product information specifies adjustment from 0.1°C to 15°C |
| P2 | Upper Setpoint Limit | Restricts the highest temperature the user can select |
| P3 | Lower Setpoint Limit | Restricts the lowest temperature the user can select |
| P4 | Temperature Correction | Applies an offset to the displayed temperature; supplied product information specifies approximately -7°C to +7°C |
| P5 | Delayed Start | 0–10 minute relay start delay |
| P6 | High-Temperature Alarm | Available on some W3230 firmware revisions |
| P7 | Data Lock / Setting Protection | Available on some W3230 firmware revisions |
| P8 | Factory Reset | Available as a menu function on some W3230 firmware revisions |
Some units provide only the core P0–P5 functions while others also expose P6, P7 or P8. Parameter ranges and the exact factory-reset procedure can also vary. If your menu stops earlier than shown above, use the functions actually presented by your controller rather than attempting undocumented settings.
Heating, Cooling & Hysteresis
Cooling Mode – P0 = C
In cooling mode, the relay switches on when the measured temperature reaches or rises above the setpoint. It switches off after the temperature falls by the P1 hysteresis amount.
Example: SV = 25°C and P1 = 2°C. Cooling switches on at approximately 25°C and switches off after the temperature falls to approximately 23°C.
Heating Mode – P0 = H
In heating mode, the relay switches on when the measured temperature reaches or falls below the setpoint. It switches off after the temperature rises by the P1 hysteresis amount.
Example: SV = 25°C and P1 = 2°C. Heating switches on at approximately 25°C or below and switches off after the temperature rises to approximately 27°C.
A very small P1 value keeps the temperature close to the setpoint but can cause frequent switching. A larger value reduces relay cycling but allows a wider temperature variation.
Start Delay – P5
P5 adds a delay before the relay is allowed to start again. A setting of 0 disables the delay. This is particularly useful with refrigeration equipment, where repeated rapid restarts can damage a compressor.
For compressor applications, set P5 according to the equipment manufacturer's required minimum restart interval rather than relying only on the thermostat setting. The OUT indicator may flash while the delay timer is active.
Temperature Calibration – P4
P4 lets you correct a consistent offset between the W3230 reading and a trusted reference thermometer.
Place the W3230 probe and reference sensor together in a stable environment and allow both readings to settle. Calculate:
Correction = Reference Temperature − W3230 Displayed Temperature
For example, if the W3230 shows 24.5°C while the reference shows 25.0°C, set P4 to approximately +0.5°C.
An NTC thermistor is non-linear. A correction made at room temperature may not produce identical accuracy across the entire temperature range. For demanding applications, compare the controller with a suitable reference near the actual operating temperature.
Keep the controller body, terminal block and electrical connections dry. Do not assume the controller enclosure, probe cable joint or connectors are waterproof simply because the stainless probe is described as waterproof.
Troubleshooting
No display
- Measure the supply voltage directly at +VCC and -GND.
- Confirm the controller is receiving approximately 12V DC.
- Check DC polarity.
- Do not power the stocked 12V unit from 24V or mains voltage.
PV shows LL or LLL
- This normally indicates an open or disconnected temperature sensor.
- Check the probe cable and its connection to the controller.
- Look for broken, crushed or damaged sensor wiring.
- If replacement is required, use a compatible NTC 10k temperature probe rather than a thermocouple or digital temperature sensor.
PV shows HH or HHH
- The measured temperature may be beyond the supported measurement range.
- Check whether the probe is actually exposed to excessive temperature.
- Inspect the probe and cable for damage if the displayed condition is not plausible.
OUT indicator turns on but the load does not operate
- Remember that S1 and S2 are relay contacts, not a powered 12V output.
- Confirm that the load's power circuit passes through S1 and S2 in series.
- Measure the load supply voltage.
- Check fuses, wiring and the load itself.
- Temporarily use a small known-good 12V load when diagnosing the controller.
Relay does not turn on when expected
- Confirm P0 is set to the required H heating or C cooling mode.
- Check the PV temperature, SV setpoint and P1 hysteresis.
- Check whether P5 start delay is active. A flashing OUT indicator normally means the controller is waiting for the delay period.
- Check for sensor or high-temperature alarm indications.
Relay switches too frequently
- Increase the P1 hysteresis value.
- Check that the sensor is not directly beside the heater, cooler or fan outlet.
- For compressors, configure an appropriate P5 restart delay.
- Improve sensor placement so it measures the controlled environment rather than a local hot or cold spot.
Temperature reading appears incorrect
- Allow the probe enough time to reach the temperature of the material or air being measured.
- Compare it with a suitable reference thermometer.
- Use P4 to correct a consistent offset.
- Avoid unnecessarily extending the NTC sensor cable because added resistance can affect the indicated temperature.
Load stays on continuously
- Check that the load has not been wired directly across its supply and bypassed the relay.
- Verify P0, the setpoint and P1 hysteresis.
- If the OUT indicator is off but S1 and S2 remain electrically closed, the relay contacts may have been damaged or welded by an overload or excessive inrush current.
Settings cannot be changed or do not behave as expected
- If your firmware includes P7 data lock, check whether it is enabled.
- Exit the menu and enter it again before changing further parameters.
- W3230 firmware versions differ, so do not assume another online manual has exactly the same P6–P8 behaviour as your unit.
This guide applies to the AuscomTech W3230 DC 12V version. W3230 hardware and firmware revisions can differ in parameter ranges, menu functions and reset behaviour. Always follow the voltage and terminal markings on the controller in hand. The advertised relay-current figure must not be treated as a guaranteed continuous rating for every load type. Use suitable fusing and external switching hardware for high-current or high-inrush loads. For applications where overheating, freezing or equipment failure could cause damage or injury, use an independent safety cut-out or other appropriate fail-safe protection rather than relying on the W3230 as the sole safety device.