English Manual for DoCooler Temperature Controller H9745

So I got this temperature controller from Amazon to control the temperature of a freezer. I bought the Farenheit version for about $16.

It's a great little item that I've used a few times to replace freezer thermostats for a beer cooler or fermenter.


But the operating instructions that come with it are pretty bad. Obviously written by a non-English speaker.

The number on the display while it's operating is the current thermostat temperature. So in the picture above, the temperature sensor is at 88.6F.

This controller can be in two main modes:

• Heat mode - the controller will supply power if the thermostat reads under the set temperature, i.e., you are trying to keep something warm by supplying power to a heating device.
• Cool mode - the controller will supply power if the thermostat reads over the set temperature, i.e., you are trying to keep something cool by supplying power to a cooling device. 

Not shown on the picture above are two red dots on the far left of the digital display, one to the right of the word Heat, and one to the right of the word Cool.

• If the Heat light is on it means that the controller is in Heat mode, and the controller is supplying power. (Hey, it's too cool, I'll turn the heat on for you.)
• If the Cool light is on, it means that the controller is in Cool mode, and the controller is supplying power. (Hey, it's too hot. I'll turn the cool on for you.)
• If neither the Heat or Cool light is on, the temperature controller is not supplying power. But with no lights, you can't see if it's in Heat mode or Cool mode. It's either in Heat mode and warm enough, or Cool mode and cool enough.

Basic Settings

These are the items to change to get up and running. The defaults for the other settings are generally ok.

Changing from Heat mode to Cool mode

1. Hold the S or Set key for about three seconds until the display shows HC. Release the key. 
2. Press and release the S/Set key. H or C should show on the display and blink.
3. Use the up or down arrows until the mode you want is showing: H or C.
4. Press and release the S/Set key.
5. Wait about three seconds. The display should now be showing the current temperature.

Changing the set temperature

1. Press and release the S/Set key.The display will blink the current set temperature.
2. Press and release the up or down arrow keys to change the set temperature. If you hold the up or down arrow key for 3 seconds, it will begin to adjust up or down more quickly.
3. When you are at the temperature you want, wait about three seconds. The display will stop blinking and go back to showing the current thermostat temperature.

Advanced Settings

You might want to change these things depending on your application.

Adjusting the Hysteresis

The pamphlet that comes with the controller calls this the "slewing range of temperature". You can read about hysteresis in control systems on Wikipedia.

This is basically the "slop" around the set temperature to keep the controller from switching on and off too rapidly. The slewing range is in degrees fahrenheit.

Example: Assume you want to keep something at 40F, and the slewing range is set to 2F (the default). Then the temperature controller will not turn on until the temperature rises to at least 42F (40F + 2F). It will turn on, powering the cooling device, until the temperature reads 40F, then turn off. The temperature will likely continue to drop, to, let's say 38F. Then the temperature will start to rise. When the temperature reaches 42F, the controller will turn on again.

To adjust:

1. Hold the S or Set key for about three seconds until the display shows HC. Release the key. 
2. Press the up or down arrow until the display shows CP.
3. Press and release the S/Set key. The current slewing range value will blink (the default is 2, meaning 2F).
4. Use the up or down arrows until the slewing range value you want is showing: 1-30.
5. Press and release the S/Set key.
6. Wait about three seconds. The display should now be showing the current temperature.

Adjusting the Time Delay

The pamphlet that comes with the controller calls this the "delayed start". 

This is similar to the hysteresis - it is used to keep the controller from switching on and off too rapidly. The Time delay is in minutes.

This is the number of minimum number of minutes between the controller turning off, then turning back on again.

To adjust:

1. Hold the S or Set key for about three seconds until the display shows HC. Release the key. 
2. Press the up or down arrow until the display shows PU.
3. Press and release the S/Set key. The current time delay value will blink (the default is 2, meaning 2 minutes between turning off and turning on).
4. Use the up or down arrows until the time delay value you want is showing: 0-10.
5. Press and release the S/Set key.
6. Wait about three seconds. The display should now be showing the current temperature.

Temperature Correction

If you think your thermostat is not correct, you can adjust the controller by plus or minus ten degrees fahrenheit.

To adjust:

1. Hold the S or Set key for about three seconds until the display shows HC. Release the key. 
2. Press the up or down arrow until the display shows CA.
3. Press and release the S/Set key. The current temperature adjustment value will blink (the default is 0.0, meaning there is no adjustment).
4. Use the up or down arrows until the temperature adjustment value you want is showing: -10.0F to 10.0F
5. Press and release the S/Set key.
6. Wait about three seconds. The display should go back to showing the current temperature.

Operating Limits

You can adjust the temperature range in which the controller will operate. By default the range is -58F to 194F. With these settings, if the temperature drops below -58F, the display will blink "LLL" and will not provide power. If the temperature rises above 194F, the display will blink "HHH" and will not provide power.

To adjust the upper limit:

1. Hold the S or Set key for about three seconds until the display shows HC. Release the key. 
2. Press the up or down arrow until the display shows HA.
3. Press and release the S/Set key. The current upper limit value will blink (the default is 194F).
4. Use the up or down arrows until the upper limit value you want is showing.
5. Press and release the S/Set key.
6. Wait about three seconds. The display should go back to showing the current temperature.

To adjust the lower limit:

1. Hold the S or Set key for about three seconds until the display shows HC. Release the key. 
2. Press the up or down arrow until the display shows LA.
3. Press and release the S/Set key. The current lower limit value will blink (the default is -58F).
4. Use the up or down arrows until the lower limit value you want is showing.
5. Press and release the S/Set key.
6. Wait about three seconds. The display should go back to showing the current temperature.

Other models that these instructions might work for

Based on the pictures, these controllers seem to be almost exactly the same product.

• Lerway Temp controller
• Inkbird Temp controller