We had the capillary tube/bulb/thermistor/sensor/thingamajig on our roof AC unit pushed really deep, up into the ventilation intake for the roof air. I have heard that this can give a false reading of cool air inside the airbox, while the interior of the coach never quite cools down enough....
Look for an uninsulated, thicker "copper" solid-core type wire on the intake side of the roof air unit. The wire should be pliable and bendable, but not bent at sharp angles. (You will have to remove the filter and/or the shroud to access) Make sure that this conductor is at the same level/close to the open foam air filter media of your intake to the Roof air. Make sure you do not put any sharp angles on the conductor as it could fatigue and break off. (Think of flexing a wire coat hanger over and over....*snap!*
Give time for the system to adjust to the new thermal zone in the intake and I think you'll be pleased with the result. It's not going to get you down to deep freeze temps, but you should notice a difference.