Table 2-2. Unit Troubleshooting
TEST OR INSPECTION
Before you use this table, be sure you have performed all applicable preventive
maintenance checks and services.
WATER HEATER FAILS TO START.
Step 1. Use ac voltmeter and check for 208 V ac incoming voltage to water
heater control box. Measure voltage between any two legs on the red
(R), black (BK), or blue (BL) wires behind load limit switch. Refer
to water heater wiring diagram (FIG. 2-5).
a. If voltage is low or not present, check generator set for
proper function. Refer to TM 5-6115-585-12.
b. If voltage is 208 5 V ac, proceed to next step.
Step 2. Check for defective overload switch heaters. With power off, measure
for continuity across heater terminals.
a. If continuity is not found, replace heater.
b. If continuity is found, go to next step.
Step 3. Check low water probe for loose or corroded connection, broken
insulator, or shorted circuit. Check for water leaks around base of
a. Clean or replace probe as needed.
b. If probe is not defective, proceed to next step.
Step 4. Check for defective low water relay. With power off, measure a low
resistance between terminals 1 and 2. Make a similar measurement
between terminals 9 and 10 on low water relay.
a. If either measurement is open, notify your supervisor.
b. If continuity is indicated on both measurements and problem
persists, notify your supervisor.