Majestic L6-4.0L (1990)
Thermal Limiting Fuse: Description and Operation
Superheat Switch and Thermal Fuse
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A SUPERHEAT SWITCH is included in the compressor clutch circuit to provide a compressor protection system. The SUPERHEAT SWITCH
and THERMAL FUSE guard against a low refrigerant charge or blockages causing extreme superheated refrigerant vapor conditions resulting in
compressor damage. The THERMAL FUSE is a sealed unit containing a heater and a meltable fuse. The SUPERHEAT SWITCH is located in the
rear of the compressor in contact with the suction side refrigerant vapor. With a low refrigerant charge or a blockage the pressure drops and the
temperature rises. This condition closes the SUPERHEAT SWITCH contacts which completes the THERMAL FUSE heater circuit, melts the
fuse, disconnects the battery supply to the compressor clutch winding and the THERMAL FUSE heater. The compressor ceases to operate and
damage from insufficient lubrication will be avoided.
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The thermal fuse melts at-- 157° to 182°C (314° to 359° F).
Time taken:
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2.0 minutes at 14 V
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5.5 minutes at 11.5 V
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The heater resistance cold-- 8 to 10 ohms.
CAUTION: After a thermal fuse melts, establish and rectify the cause before replacing the thermal fuse unit complete.
