The heat in the interior from the van's heater system is controlled by a
manual switch at the end of a wire that is moved by the second lever in
the heater control setup.

The heat indicator gauge is fed by an electrical signal from a little
sensor on the engine near the thermostat.

The engine thermostat opens and closes to regulate when engine coolant
circulates to the radiator to keep the engine in an optimal temperature
range.

The heater hoses that bring warm air to the heat exchangers in both the
front and rear are on a separate loop that is not cut on and off by the
thermostat.

There is another heat sensor near the thermostat or water pump that
measures coolant temperature and sends that info to the ECU as part of
the fuel injection system.

All these things are mostly independent of one another.

Sometimes the wire that opens and shuts the heat control valve for the
front heater gets bent and will no longer shut the heater control
valve.  Solution for the summer is to remove the spare and look up under
the front of the van, near the radiator and find the valve and shut it
manually and then leave the second lever in the far left position.

Sam

--
Sam Walters
Baltimore, MD

89 Syncro GL, Zetec Inside
85 Westy Weekender
85 Mercedes Benz 300D Turbodiesel - to become veggie oil powered

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