Depress pump 1 or pump 2 local START switch and check continuity from P2 to L4. If check
indicates closed circuit, go to step (4). If check indicates an open circuit, replace faulty wire. If
check indicates an open circuit, check continuity of wires from P2 to S2 and L4 to S1. If check
indicates closed circuit in all wires, replace faulty START switch.
Check continuity of wires from L4 to M1, M2 to N1, and N2 to TB14. If check indicates closed
circuit, go to step h. If check indicates an open circuit, replace faulty wires.
h. If no fault was found in steps e thru g, replace main contactor.
4-7.2.7 Cooling pump motor controller
Make sure cooling pump motor controller is electrically dead before starting repair
or removal. Redtag power panel 1 circuit breaker 1P5 with: "WARNING - DO NOT
ACTIVATE. REPAIRS BEING MADE."
4-188.8.131.52 Cleaning and inspection
Make sure cooling pump motor controller is electrically dead by opening (OFF) power panel 1 circuit
breaker 1P5. Redtag circuit breaker with: "WARNING - DO NOT ACTIVATE. REPAIRS BEING MADE."
Wipe clean exterior of motor controller with clean rag. Open motor controller door and vacuum clean or
clean inside with electrician's brush. Avoid using solvents for cleaning inside of motor controller.
Solvents leave a greasy film on components that may reduce electrical continuity.
Check fuse. Replace if necessary.
Visually inspect for indications of burns, corrosion, loose connections, damaged parts, or chipped paint.
Clean corrosion from contacts and terminals, tighten loose connections, and replace damaged parts.
Clean electrical contacts with silver polish, fine sandpaper, or burnishing tool. DO NOT use emery paper
or steel wool. Vacuum to remove residue. Touch up paint according to TB 43-0144.
4-184.108.40.206 Test and repair
With power panel 1 circuit breaker 1P5 closed (ON), check motor controller input line voltage across
points A1 and B1, B1 and C1, and A1 and B1 (Figure 4-2). If voltage across any terminal pairs is 0 power
source is at fault, go to step b to correct problem. If voltage across all three terminal pairs of points is
440, go to step c.
Check circuit breaker 1P5 output line voltage. If voltage across any terminal pairs is 0, circuit breaker or
power source is at fault. If circuit breaker voltage across all three terminal pairs is 440, replace power
cable from circuit breaker to motor controller.
Close motor controller disconnect switch and check line voltage across points A2 and B2, B2 and C2, and
A2 and C2. If voltage across any terminal pair is 0, check main contactor contacts. If bad or corroded,
clean or replace contacts. If contacts are good, replace disconnect switch. If voltage across all three
terminals is 440, go to step d to check motor controller output voltage.
Check output voltage across points T1 and T2, T2 and T3, and T1 and T3. If voltage across any terminal
pairs is 0, go to step e. If voltage across all three terminal pairs is 440, check motor connections and
continuity of wires from motor controller to motor. If connections and wires are good, replace motor.
Check voltage of overload protection thermal units across points N1 and T1, N2 and T2, and N3 and T3.
If voltage across any terminal pair is 0, replace faulty overload protection thermal unit. If voltage across
all terminal pairs is 440, go to step f.