Thermal Limiter Conversion - UE43934NF

Early model GM vehicles through 1977 use a superheat switch, along with a thermal limiter fuse, for a system protection device. This same system has been used on later models of Jaguar, Mercedes Benz and others. For a variety of reasons it has become desirable to convert this system to a pressure switch style setup. 

The superheat (CD5998) switch is a normally open switch that closes to ground with high temperature or pressure. This causes the heater to burn the fuse, and opens the clutch circuit. CD5998 is used with the original A6 Compressor (UE43934).

The high pressure (JLM1165-X) switch or switch kit (MC1315-X + PT1032-X) is normally closed to ground to complete the clutch circuit and opens with high pressure to shut off the clutch circuit. JLM1165-X or MC1315-X/PT1032-X are used with repacement compressor UE43934NF.

The superheat switch can only be used in compressors made for a superheat switch (57052 compressor body with various clutches). To convert to a pressure cut out system, first change the compressor to a pressure switch type that matches the original in clutch configuration, etc. After the pressure switch is in place, a minor wiring change is necessary as detailed below. 

Dispose of the thermal fuse. Jumper terminals "B" & "C". Thermal "S" will not be used. Take the clitch wire that was the ground and attach it to the pressure switch.