Keith,
The correct engine temperature is the one on the Silverleaf, and at 179 degrees your engine was too cold to need the radiator fan. As for the fan/fans on the engine access door, there is no way to determine how they are powered without tracing the circuit. Many of those fans where aftermarket installations on the 2002 Marquis coaches. If yours are an aftermarket installation, and most are, there are several different types of circuits used to power them. However if they are factory, the circuit was generally wired for the fans to come on at start-up and run for thirty minutes after shut down with no regard to engine temperature since the bay door fans do not cool the engine. Those fans are designed to lower your bedroom temperature by cooling the engine bay area and that has no effect on engine operating temperature.
The dash gauge and the filter bay gauge probably are using the same sensor and the wiring and gauges are responsible for the difference in the readings. Like I have always said, analog dash gauges are for "Entertainment Purposes Only", so if you want accuracy look at the Silverleaf.
Gerald
