Chapter 7 Compressor Parts
77
Wiring Instructions - Murphy Latching Relay
Kit (99903401)
This kit contains the parts and instructions needed to install the 117 Murphy latching relay on
IMT Commander IV models with rotary screw air compressors. The Murphy latching relay
replaces the compressor shutdown relay on all three wiring revisions.
1
Find the shut down relay, which is present on all three wiring revisions. The relay can be
found by locating the Murphy temperature switch gauge. Look at the back of the switchgauge
and find the black wire; this wire will connect to terminal 85 of the shut down relay. If the
black wire can not be followed visually, a continuity test can be performed to find the relay.
One at a time, remove the relay from the base and check continuity from terminal 85 to the
black wire on the switch gauge.
2
Place and mount the bracket that will hold the Murphy latching relay. The bracket can be
placed as shown in the picture below. Use the ¼” bolts, washers and nuts supplied in the kit
to attach the bracket to the compressor control panel. A grommet is supplied to pass the
wires through the panel to the Murphy relay. See figure 1.
