The electronic unit is a dual voltage device. This means that the same unit can be used in both 12V and 24V power supply systems. Maximum voltage is 17V for a 12V system and 31.5V for a 24V power supply system. Max. ambient temperature is 55°C. The electronic unit has a built-in thermal protection which is actuated and stops compressor operation if the electronic unit temperature gets too high.Installation (Fig.1)Connect the terminal plug from the electronic unit to the compressor terminal. Mount the electronic unit on the compressor by snapping the cover over the screw head(1).Power supply (Fig.1)The electronic unit must always be connected directly to the battery poles (2). Connect the plus to + and the minus to -, otherwise the electronic unit will not work. The electronic unit is protected against reverse battery connection.For protection of the installation, a fuse (3) must be mounted in the + cable as close to the battery as possible. 15A fuse for 12V and 7.5A fuse for 24V circuits are recommended.If a main switch (4) is used, it should be rated to a current of min. 20A. The wire dimensions in Table. 2 must be observed. Avoid extra junctions in the power upply system to prevent voltage drop from affecting the battery protection setting.Battery protection (Fig.1)The compressor is stopped and re-started againaccording to the decided voltage limits measured onthe + and - terminals of the electronic unit. The standard settings for 12V and 24V power supply systems appear from Table. 3. Other settings (Table. 1) are optional if a connection which includes a resistor (9) is established between terminals C and P.Thermostat (Fig.1)The thermostat (7) is connected between the terminals C and T. Without any resistor in the control circuit, the compressor with electronic unit will run with a fixed speed of 2,000rpm when the thermostat is switched on. Other fixed compressor speeds in the range between 2,000 and 3,500 rpm can be obt