Purpose of Refrigerator Tag Line Circuit on 9-Way Trailer Connector

Question:

What is a refrigerator tag line? What is its purpose? What does it connect to on the truck? Any information would be appreciated.

asked by: Clyde

Expert Reply:

The refrigerator or reefer tag line is the power feed for the thermostat that controls the cooling unit on a refrigerated trailer. It would connect to a 12-volt power source on the truck, if needed. If you are not pulling a refrigerated trailer, the circuit could be used for another purpose or just left unconnected if you do not need it.

I have provided a wiring diagram for a 9-way connector that you might find helpful.

expert reply by: Mike L