Coleman furnace question
An "upper limit" or "high limit" in a forced-air furnace is generally intended as a safety device, not for ordinary use to stop the burner. The thermostat controls of a properly designed system will only stop the burner when the room temperature reaches the desired temperature. In other words, the furnace should run constantly, with fan air-flowing, until the thermostat shuts off the burner. 

The fan may have a dirty filter, closed registers or other obstructions that restrict the airflow and trigger the safety of the upper-limit switch. The system may be too large for the target living spaces. A gas-fueled fire may be burning overly hot for some reason. A good technician may assist in pinpointing the exact cause of a high-limit problem.

In many systems, such switches require a manual reset and can only be reset once without knowing additional "magic", to avoid untrained homeowners from bypassing the built-in safety.