Fuel Heater

The fuel heater is located between the top of the fuel filter and the filter element. It is serviced independently from the rest of the system. Power (approximately 200 watts) is available to the fuel heater whenever the key is in the "ON" position, but is used only when the fuel is cold.

A bimetallic snap switch is located below the connector, and is exposed to diesel fuel contained in the fuel filter. The snap switch senses fuel temperature and operates within a temperature range between 30-55°F (-1-13°C). This means that the heater will be operating at a fuel temperature of 30°F (-1°C) or lower and must cease operating at a fuel temperature of 55°F (13°C) and above.

When the switch snaps into the "ON" position, it supplies current through a relay (mounted on the glow plug module bracket panel) to a positive temperature coefficient (PTC) heater. This is self-regulating because as its temperature goes up, so does its resistance to electrical flow, thereby limiting the maximum temperature.