TM 9-2350-230-12
Malfunction
Probable cause
Corrective action
WINTERIZATION COOLANT -
HEATER - Continued
65. Heat output too low
a. HI-LO switch on LO
a. Switch to HI.
b. HI-LO switch defective
b. Check switch (table 8-14.
1)
and replace if defective.
c. Defective coolant thermostat.
c. Check thermostat (table
8-14.
1) and replace if
defective.
d. Clogged filter in pump or
d. Clean or replace filter(s)
line
e. Excessive carbon in burner
e. Replace heater.
f. Defective fuel valve
f. Replace heater.
66. Heater burns on high
Defective diode
Check diode (table 8-14.
1).
heat continuously,
If defective replace heater.
even when switched to
LO.
66. 1 Heater will not
a. Open circuit
a. Check circuit #563 (table
operate on high heat
8-14.1). Repair or re-
place harness as necessary
b. Defective coolant thermo-
b. Check thermostat (table
stat
8-14. 1). Replace thermo-
stat if defective.
c. Defective restriction thermo-
c. Check thermostat (table
stat
8-14.1). If thermostat is
defective, replace heater.
d. Defective restriction solenoid
d. Check solenoid (table 8-14.1).
If defective, replaceheater:
e. Defective diode
e. Check diode (table 8-14.1).
If defective replace heater.
f. Excessive carbon in heater
f. Replace heater.
66. 2. Blower and coolant
efective flame detector
Replace switch (fig. 12-12).
circulating pump con-
switch.
tinue to operate more
than 5 minutes after
heater shuts off.
8-28.2
