Here is a how-to video showing how to replace the temperature controller on your horizon model upright refrigerator or freezer, should the need arise. This is a simple process and written instructions for you to follow are included with the replacement part. If the current controller is still active you can retrieve the settings from it prior to removal then program them into the new controller. After writing down the current settings remove both main power and the backup battery to power the unit down. Make sure to note the location of the wire connectors and transfer them over to the same connections on the new controller as you remove and replace. Taking a picture or writing down the wire locations are a helpful tip when replacing components. After the new controller is installed power the unit back on and reinstall the backup battery. At this point you can program the new controller. We also recommend checking the temperature calibration. This is simply done by placing a calibrated independent thermometer in the probe bottle with our monitor probe and make sure the temperature reading corresponds to the temp reading on the display. If the calibration is off or if the unit does not stabilize at the correct temperature adjustments can be made to the settings to correct this. Your Helmer service manual will have complete instructions on adjusting the temperature or calibration. You can also give us a call and one of our in-house technicians can answer any questions or help walk you through the process.