[wingnut60]

Cyndy,

Most trucks don't put out enough amps to do more than maintain a battery charge state, even if very little is being used. You can't get enough power from the truck to do any more than that. First thing to do is check the direct 12 volt line at the plug in the bed--it should always be hot if the vehicle is running, but not if it is off. No power at the plug, no hope of getting power to keep the batteries up. If the plug is hot, then you have to look in the owners manual to locate the fuse (and there may be more than one).
Do I understand you to say you are running the refrigerator on 110 volt house power from the inverter? If so, you will never generate enough truck power to make up the loss. Is this part of your ongoing refrigerator problems?

Going from the tow truck to the batteries to the inverter to the refrigerator is very inefficient, there is too much resistance loss in the process. Using 12 volt from the batteries is much better, that MAY be offset by the power from the truck. AND, you need to start off with fully-charged batteries.

Joe