Model MPC-1L, MPC-22, MPC-554
3-4
Oct. 2018
FM06-038-B
4. With the component energized, 0 volts should show on the
output side of the relay, and 5 vdc on the input side. Also,
check for correct polarity into the relay-reference wiring
diagram.
5. If voltage varies from steps 3 and 4, remove power to unit
pull input wires from relay and place leads of meter onto
input wires. Reapply power to unit. When unit is running,
if the input wires to relay shows 5vdc, the relay is faulty.
6. Uplug power cord to unit.
7. Label and remove wires from relay. Figure 2.
8. Using a 5/16” socket or wrench, remove the 2 nuts securing
the relay and pull relay from panel. Figure 3.
9. Install new relay in reverse order, making sure not to reverse
the polarity on the relays - reference wiring diagram.
3-5. RELAY REPLACEMENT
(Continued)
Figure 2
Figure 3
