Plus AND Minus 12v from AC to Thermostat
I have a Dometic A/C and a Dometic single zone thermostat. The thermostat requires plus AND minus 12 volts. The schematic of the A/C control box indicates that the plus AND minus 12v come from the pow...
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Can't find any data on 3313379.000, but did find this link which I believe to be a similar Dometic single zone control kit / thermostat. These aren't your typical thermostat installations as many have already suggested. Which is why its important to have information on specifics.
The wiring diagram for this unit on the last page, assuming its similar to yours, shows the connections. Three wires to the thermostat from the control box. Red, black, and orange. The red is +12V from control box, the black is 12V ground or the negative terminal of the battery, and the orange is a data wire that carries all of the control signals. All three connect between the thermostat and control box. The black wire at control box also connects to 12V ground (negative). A separate wire on the control box connects to 12V from the converter or battery. This is the +12V supply line. The control box may or may not do something to switch the 12V its supplying to the thermostat, but it is supplying the 12V.
So, answering your original question again, when you disconnect 12V from the control box, you disconnect it from the t-stat. The red and black lines should have 12V on them and the orange won't necessarily have a readable or reliable voltage since it is a data wire.
The wiring diagram for this unit on the last page, assuming its similar to yours, shows the connections. Three wires to the thermostat from the control box. Red, black, and orange. The red is +12V from control box, the black is 12V ground or the negative terminal of the battery, and the orange is a data wire that carries all of the control signals. All three connect between the thermostat and control box. The black wire at control box also connects to 12V ground (negative). A separate wire on the control box connects to 12V from the converter or battery. This is the +12V supply line. The control box may or may not do something to switch the 12V its supplying to the thermostat, but it is supplying the 12V.
So, answering your original question again, when you disconnect 12V from the control box, you disconnect it from the t-stat. The red and black lines should have 12V on them and the orange won't necessarily have a readable or reliable voltage since it is a data wire.
