(7) Set HI-LO switch (6) on control box to HI or LO position, depending upon
(8) Turn run-off-start switch (7) on control box to START position. Hold in that
position until indicator lamp (4) again lights. (Switch is spring-loaded and must be held
If switch (7) is moved to RUN position before indicator lamp (4)
lights, heater will not operate.
(9) As soon as indicator lamp (4) lights, turn switch (7) to RUN position, with no
hesitation at OFF position.
If engine coolant heater fails to start, turn run-off-start switch (7)
to OFF position. Repeat operations (4) through (9). if heater fails
to start after two attempts, notify organizational maintenance that
service is required.
(10) Make sure vehicle fuel tank(s) are full if engine coolant heater is to operate for
an extended period.
Do not operate engine coolant heater when running vehicle engine.
Do not idle vehicle engine to maintain operating temperature. Use
coolant heater for easy starting during standby periods.
(11) Set HI-LO switch (6) as required, for desired heater output. If switch (6) is in
HI position, heater control will automatically change to LO position whenever coolant
temperature exceeds 195° F (90° C). If coolant temperature falls below 120°F (49° C),
heater will return to HI.
(12) The LO setting is suitable for standby operation.
(13) To shut down engine coolant heater, turn run-off-start switch (7) to OFF
(14) Check indicator lamp (4) to make sure lamp goes out and blower motor shuts
down after purge cycle is completed.